oí th e posterior portion of the trigemino-facialis chamber, and then tu rn s backward in the bone, parallel
to th a t edge of the chamber. At th e anterior edge of th e subtemporal fossa th e canal tu rn s inward
in th e bounding wall of th e fossa, still lying in th e prootic, and, on one side of the head of th e one
specimen sacrificed in this examination, there seemed to end blindly a t th e hind edge of the prootic.
On th e other side of th e head of th e same specimen th e canal opened into th e subtemporal fossa, b u t
whether this opening was an artifact or not, I could n o t determine. W hat this canal is I can not
determine, b u t it may, perhaps, be a persisting remnant of th e spiracular canal of Amia.
In Albula the temporal fossa is similar to th a t in Elops, b u t its anterior portion is much less
extensive; and I find no canal opening into th e bottom of th e fossa. No special description of it
seems necessary.
In Esox, according to Vrolik’s (’73) figures of transverse sections of th e skull, tliere is, in the
temporal fossa, a mesial pocket which has the position of a preépiotic fossa. The deeper portion of
this pocket is hounded both above and below b y portions of th e supraoccipital bone, exactly as the
preépiotic fossa is, in Elops. The anterior end of th e temporal fossa ends blindly in th e thick dorsolateral
edge of th e chondrocranium, and is there pa rtly surrounded by a th in layer of perichondrial
bone which apparently belongs to th e p terotic though this is not so stated. The dorsal portion of the
alisphenoid is formed by two plates of perichondrial bone, one of which lines th e external and th e
other th e internal surface of th e cartilaginous cranial wall. The internal plate is apparently raised
into a ridge-like process, b u t whether it bounds a recess for th e dorso-anterior end of th e anterior
semicircular canal, or not, is n o t evident. The wall of th e cranial cavity, however, quite certainly
continues backward, in th e line of th e ridge-like process, until it joins th a t flange of the supraoccipital
th a t forms th e floor of th e preépiotic pocket, as it does in Elops. A region corresponding to th a t occupied
by the anterior portion of th e temporal fossa of Elops is thus, in Esox, included in th e cranial
wall, and th e sphenotic, as in Elops, is excluded from bounding relations to the cranial cavity. Assume
th a t there is, on th e dorsal surface of this p a rt of the chondrocranium of Esox, an anterior diverticulum
of th e temporal fossa similar to th e one in Amia: a simple enlargement and deepening of this diverticulum,
and its partial confluence with th e temporal groove of th e fish would produce th e conditions
found in Elops; and if the enlarged diverticulum did not become confluent with th e temporal groove,
acquiring, instead, an independent opening to th e exterior, on th e lateral surface of th e skull, it would
seem as if it must give rise to th e conditions described by Ride wood (’04c, p. 473) in Engraulis.
In th e Characinidae, judging from Sagemehl’s (’84b) descriptions and figures, th e pterotic,
and th a t bone alone, forms th e floor of th e temporal fossa. This is however not tru e of Macrodon,
which I have examined in this connection. In this fish th e fossa has anterior and posterior portions,
as in Elops, the two portions being separated b y a low saddle. The floor of the posterior portion is
formed b y th e pterotic, as Sagemehl states, b u t th a t of the anterior portion is formed b y the prootic,
th e la tte r bone having a widely spreading dorsal edge. The anterior end of th e anterior portion of the
fossa abuts against and is bounded anteriorly by th e sphenotic. The fossa is thus less extensive th an
in Elops, b u t much more extensive th a n in Scorpaena. I t has an extensive preépiotic pocket, and in
this pocket lie those fenestrations of the epiotic th a t are said to be so characteristic of th e Characinidae,
The anterior wall of th e labyrinth recess is formed by a strong flange th a t lies mainly on the prootic
b u t extends upwards slightly onto th e cerebral surface of th e sphenotic. Between this flange and the
cerebral wall of th e anterior portion of the temporal fossa, in a deep groove, lies th e anterior semicircular
canal. In the bottom of th e anterior portion of the fossa there is, in my specimen, a foramen
— if it be n o t perhaps simply a defect in the bone — which opens into th a t canal th a t leads from the
cranial cavity to the upper one of the two apertures called by Sagemehl, in his figures of Erythrinus,
the facialis foramina. The opening is so inconspicuous th a t I should not have noticed i t h ad I not been
led to look for it, because of th e canal here found in Elops. There are also in my specimen, two perforations
of th e bony partition th a t separates the temporal fossa from th e dilatator fossa, one of the
perforations undoubtedly giving passage to th e ramus oticus, and the other probably to a venous
vessel similar to th e one th a t, in Scorpaena, accompanies the oticus in its backward course, as will
be later described. These several foramina are not described by Sagemehl, and furthermore th a t
author’s descriptions of th e foramina th a t perforate the lateral wall of the prootic are certainly not
wholly correct. The so-called jugular foramen is found, as shown, opening directly into th e labyrinth
recess, b u t this opening in th e prepared skull must certainly be closed, in the recent state, b y membrane,
and hence can not transmit th e jugular vein. In the anterior edge of this foramen a small canal
begins in th e wall of the prootic and, running forward, traverses the base of th a t flange th a t forms
th e anterior wall of th e labyrinth recess and so enters a recess of the cranial cavity into which the
so-called facialis and trigeminus foramina open. This cranial recess probably lodges, as in Cottus,
and as will be fully described when describing th a t fish, the profundus, communis and lateralis ganglia
of the trigemino-facialis complex, the trigeminus ganglion probably having an extracranial position.
If th is be so, th e jugular vein, as in Cottus, does not enter the recess, b u t lies along th e outer surface
of th e skull immediately beneath th e extracranial trigeminus ganglion. One of the two foramina
marked „ fa “ in Sagemehl’s figures must then transmit th e truncus hyoideo-mandibularis facialis,
the other one, said by him to transmit a vein, probably transmitting th e encephalic branch of the
jugular vein. What th e little canal in the prootic th a t I have ju s t above described transmits, I can
not tell, and it may perhaps be an artifact.
In Catostomus teres and Moxostoma sucetta, of the Cvprinidae, th e axis of th e temporal fossa
is said by Sagemehl (’91, pp. 550—553) to lie in a frontal (transverse?) position and the fossa is said
to open on th e lateral instead of on the posterior surface of the skull. The anterior portion only of the
fossa is roofed, the roof there being formed by the mesial edge of the dermal portion of the pterotic,
the lateral edge of the epiotic (exoccipitale), and, between those two bones, by a portion of the p arietal.
In the genus Sclerognathus, the roofing portions of these several bones are said to have almost disappeared,
and in th e genus Diplophysa to have entirely disappeared; the fossa of this la tte r fish thus
becoming a simple p it or groove on the dorsal surface of the skull, the homologue, apparently, of the
groove in Scorpaena, and not of th a t in Scomber. The extrascapular and suprascapular bones are not
here considered by Sagemehl as roofing bones of the groove, b u t they are nevertheless found in all
the Cyprinidae (1. c., p. 507), the extrascapular as a small scale-like bone a t the hind edge of the
pterotic, and the suprascapular as a long, lance-like bone th a t lies along the hind edges of the pterotic
and epiotic and there roofs th e posterior entrance of the temporal groove. In certain others of the
Cyprinidae, the temporal fossa is said by Sagemehl to be reduced to a simple and narrow canal which
opens on th e posterior surface of the skull between the pterotic and epiotic. In the genera Nemachilus,
Misgurnus, Cobitis and Acanthophthalmus even this narrow canal is said to become almost entirely
obliterated.
A temporal fossa, similar to th a t of Sclerognathus, is said by Sagemehl to be found in very
many of the Physostomi and in nearly all the Acanthopterygii and Anacanthini. This I am inclined