separates into two parts, one of which turns upward and backward, in the posterior one of th e two
infranasal bones shown in th e figures, while th e other p a rt traverses th e anterior one of those two
bones an d then enters and traverses th e membrane component of the mesethmoid. This la tte r bone
alone, if it lodges two latero-sensory organs on either side, or this bone together with th e anterior
infranasal bone, if each of th e bones lodges b u t a single organ on either side, is accordingly the homo-
logue of the supraethmoid (median dermal ethmoid) of Amia; and in Elops, as in Amia, th e one or
two bones have n o t y e t become incorporated in th e premaxillary as its ascending process. The posterior
infranasal bone alone (or th a t bone together with th e anterior one, if this la tte r bone be not a p a rt
of the median dermal ethmoid) is the homologue of th e antorbital bone of Amia, and this antorbital
bone, traversed b y a latero-sensory canal, has also never heretofore been described in any teleost,
so far as I can find, unless it be in certain of the Siluridae (Allis, ’98). This antorbital bone of Amia,
and hence also th e bone of Elops, is represented in Polypterus, as I have already shown (’00b), in the
infranasal process of the premaxillary of th a t fish, and, judging from a recent work by Gaupp (’05),
it must be the homologue of th e septomaxillary of Amphibia and higher vertebrates. I t is of
dermal origin, as th e septomaxillary is, and so closely resembles th a t bone in general position and
relations to other bones th a t it seems quite unquestionably to represent i t before it has acquired its
nasal plate; th a t plate being a special and secondary acquisition, as Gaupp has shown.
In Macrodon, which I have examined, the premaxillary has a process similar to th a t in Salmo,
and similar also to th a t shown by Sagemehl in Erythrinus, where th a t author considers it as an ascending
process. This process in Macrodon articulates by its mesial edge with th e lateral edge of the
dermal component of th e mesethmoid, and is widely separated from its fellow of th e opposite side,
exactly as Sagemehl’s figures show for Erythrinus. On its internal surface there is a raised portion
which gives articulation to th e lateral surface of th e long anterior articular end of the maxillary, and
th a t th e process is simply an articular process seems quite unquestionable, the bone then having no
ascending process. And this is strictly as it should be, for th e dermal supraethmoid is here said by
Sagemehl to be fused with th e primary mesethmoid to form the median mesethmoid bone of the fish.
The supraethmoid of Macrodon would seem, however, to have been developed in relation to the
median one only of two ethmoid latero-sensory ossicles on each side, and to represent a membrane
component only of those ossicles, no latero-sensory organs here being found. The membrane component
of the lateral one of th e two ethmoid latero-sensory ossicles may then be here fused with the
articular process of the premaxillary; for th e outer surface of this process in Macrodon comes to the
level of th e adjacent dermal bones and has surface markings quite similar to those on those bones.
In Elops th e anterior infranasal bone, assumed to represent th e lateral one of th e two ethmoid latero-
sensory ossicles on either side, and which is traversed in th a t fish by a latero-sensory canal, lies directly
superficial to and in contact with th e articular process of th e premaxillary.
I t may here be further stated, th a t I find, in my specimen of Macrodon, the bone called by
Sagemehl (’84b, p. 95) the accessory palatine, and th a t, so far as can be judged from my somewhat
dilapidated specimen, it is developed in th e maxillary breathing valve of th e fish. This, if correct,
is important, for it would then be th e homologue of th e so-called vomer of Polypterus, a bone which
I, in an earlier work (’00b), identified as th e maxillary breathing valve bone of th a t fish. I t has never
heretofore been recognized in any teleost.
In Osteoglossum, according to Ridewood’s (’05a) figures, th e premaxillary has no ascending
process, and Ride wood says th a t, in this fish, th e „mesethmoid is a small rhombic bone of ectosteal
origin“. If this bone is of dermal and n o t of perichondrial origin, it would seem as if it must be a
supraethmoid instead of a mesethmoid, and th a t it must represent the missing ascending processes
of the premaxillaries.
In th e Cyprinidae, I can not determine whether the ascending processes of Sagemehl’s descriptions
are those processes o r a rticular processes. In a specimen of Tinea th a t I have examined,
there is b u t one process on th e premaxillary, and it is in contact, in th e median line, with its fellow
of th e opposite side, as an ascending process should be. I t seems however highly probable th a t this
process is simply an articular process, or perhaps th a t process fused with an ascending process. The
ascending process would certainly be w anting if, as Sagemehl states, the mesethmoid in th e Cyprinidae
has, as in th e Characinidae, an overlying dermal component fused with it. There is in Tinea, as
Sagemehl describes for others of th e Cyprinidae, a ligamentous band th a t connects the process of the
premaxillary with th e top of th e ethmoid bone, and associated with the ligament there is a small
median bone, th e rostral of Sagemehl’s descriptions; and the apparent homologue of this ligament,
in Scorpaena, is associated with th e articular ra th e r th an with the ascending process of the premaxillary.
The ascending process of the premaxillary in Amphibia and higher vertebrates is called by
Gaupp th e prenasal process of th a t bone. As this process in fishes quite certainly arises by the fusion
of the supraethmoid with the premaxillary, th e term supraethmoid process would seem a be tte r one,
if a change is to be made. And as the antorbital bones of Amia and Elops, and th e septomaxillary of
amphibians certainly do n o t belong, in their origin or development, either to th e orbital or maxillary
series, either infranasal or extranasal would seem to be th e proper term; extranasal being the term
proposed by Gaupp for the bone in the Amphibia.
The articular process of the premaxillary has never heretofore been specially described, so far
as I can find, excepting b y myself in Scomber and by Brooks (’84) in Gadus aeglifinus. I t is, however,
of very general, if not constant occurrence in th e Acanthopterygii and Anacanthini. I find it in all
th e mail-cheeked fishes th a t I have examined, and also in Zeus faber, Uranoscopus scaber, Mugil capito,
Sphyraena vulgaris, Gobius cruentatus, Trachurus trachurus and Lophius piscatorius, and more or
less completely fused with th e ascending process in Labrus, Crenilabrus and Chrysophrys aurata.
I t is also shown, in a more or less definite manner, by Cuvier and Valenciennes (’29) in their figures
of Perea, Sciaena and Otolithus; by Bruhl (’91) in his figures of Rhombus and Labrax; by Agassiz
(’33/43) in his figures of Ophidium and Vomer; by Shufeldt (’85) in his figures of Micropterus; by
Supino (’01/02) in his figures of Pomatomus, Hoplostethus, Ruvettus and Macrourus; by Traquair
(’65) in his figures of Hippoglossus; by Girard (’51) in his figures of Triglopsis; and in Gasterosteus,
judging from Swinnerton’s (’02) figures, it is probably present in much th e same condition th a t it is
in Scomber. In th e Characinidae, and possibly also in th e Cyprinidae, it is found, as I have just
above described. In th e descriptions th a t I have of other teleosts I can n o t positively recognize it.
I t would seem to be present in Argyropelecus (Supino ’01/02), th a t fish certainly having an important
ascending process. In Clupea harengus I find, on the internal surface of th e premaxillaries, a small
articular eminence th a t m ay perhaps be its homologue; but, to definitely determine this, a much more
careful study of th e bones and ligaments is needed th an I have been able to a t present give them.
In Silurus glanis there is, on th e dorsal surface of the premaxillary, a t the lateral edge of the mesethmoid,
a small process against the lateral surface of which the maxillary abuts, if n o t articulates. This
process is shown in Jaq u e t’s (’98) figure 39, and would seem to be an articular process. In Esox, a