paradoamm, the specific name indicating the extraordinary compound of characters he stated
it to possess. To a mouth, he says, as slightly armed as in the Medusae, there succeeds a
short canal, ending in a stomachal cavity in which digestion is effected; when, the more solid
parts being ejected again, the liquid and finer products of digestion pass into a branched
intestine, the main trunk of which extends down the centre of the body, terminating in a
very minute anus. The branches from this central trunk pass off symmetrically on each side,
ending, it is stated, in a narrow marginal canal that entirely surrounds the body; from the
lateral branches arise caeca going into the dorsal papillae. These are terminated by an ovate
vesicle, through which he conceives the products of digestion to enter into the blood.
Accompanying the extensive development of this so-called gastro-vascular system, M. de
Quatrefages states that he found the vascular system very incomplete; the veins had
disappeared, and their place had been taken by a system of lacunes without walls, in which
the viscera could freely float. At the same time he considered that true branchiae were
wanting in this animal, that function being likewise in part performed by the gastro-vascular
apparatus. M. de Quatrefages was, we believe, the first to describe the coloured glandular
portion of the papillae of these Mollusks,' as the true liver broken up into fragments.
In communicating to the ‘Annals of Natural History/ for October, 1843, the discovery of
a new Nudibranchiate Mollusk on the Devonshire Coast, possessing a highly ramified digestive
system, and referred to the genus Calliopeea, we took the opportunity of expressing our dissent
from some of M. de Quatrefages’ views, and gave our reasons for believing that his genus
Eolidina was founded upon a species of Eolis imperfectly understood. In the same paper we
stated that the ovate vesicles, which we had also observed at the ends of the papillae, had an
external opening, through which elliptical bodies with long hair-like tails were occasionally
discharged.* We likewise announced the discovery of organs of hearing in the Nudibranchs,
similar to what M. Siebold had described in the Conchifera and the pulmoniferous Gasteropods;
and at the same time gave our reasons for believing that the sense of smell was located in the
dorsal tentacles, a statement which subsequent observations have tended to confirm.
Pursuing still further his investigations into the evidence afforded by these animals of a
supposed degradation of the Molluscan type, M. de Quatrefages published, in March, 1844,
another memoir on the subject, in which he describes five new genera, named Zephyrina,
Adeonia, Amphorina, Pelta, and Chalidis ; all more or less deficient, according to his statement,
in some of the characters hitherto supposed to belong to the true Mollusca.f Thinking that
the anatomical characters he had detected were sufficient to unite them into a group, he
proposed to detach the Eolididce from the other Nudibranchs, and uniting them with the
Adeeon of Oken, and the genera above mentioned, to make of them a new order, under the
name of Phlebenterata. (The union of functions supposed to be indicated by the peculiar
branching of the stomach he afterwards proposed to call Phlebenterism.) The order is
characterised as “ Gasteropodous Mollusca, with the circulation imperfect or wanting, and
deprived of respiratory organs properly so called.”
In all the new genera described in the memoir, neither heart, arteries, nor veins could
be found; the vascular system is consequently supposed to be entirely wanting; its place
being supplied by the branching of the stomach, as already stated. In three of the genera, the
* This has since been recognised as an urticating apparatus.
t ‘ Annales des Sciences Naturelles/ 3d ser., v. 1, p. 129.
anus was considered to be absent. The alimentary system of these Mollusks was thus
reduced to a single opening for the reception of food and the rejection of excrementitious
matters, a condition hitherto only known to exist among the inferior divisions of the
jUadiata*
“ The Mollusks whose history I have now given,” says M. de Quatrefages, “ appear to
me to merit the especial attention of zoologists. In the vicinity of animals which all
naturalists place in the class Gasteropoda, we see them preserve the general aspect and
external characters from which this large group derives its name, but, at the same time, we
see their organisation depart in such a manner from the primitive type, that the principal
systems of vital organs are modified profoundly, and that two of them, which are generally
considered essential, disappear.” “Eolis, Calliopcea, Zephyrina, &c.,” he adds, “ are so
evidently gasteropodous Mollusks, by their external form, that all naturalists have referred
them to this extensive group. To Pelta and Chalidis the same place would certainly be
assigned, yet the anatomical characters of these animals exclude them not only from the class
Gasteropoda, but even from the department of the Mollusca.” f
This Memoir was presented to the French Academy of Sciences, and a commission of
that learned body was appointed to report upon it. The report, drawn up by M. Milne
Edwards, spoke very favorably of M. de Quatrefages’ researches, which were described as
leading to results highly important in the history of the Mollusca; and it further expressed an
opinion that among the works by which zoology had been enriched for many years, there
was, perhaps, not one which embraced so great a number of new and curious facts. This
report was adopted by the Academy, as was also a resolution expressing the importance of
making similar researches on the Phlebenterata of the Mediterranean.
In consequence of this recommendation, M. de Quatrefages was sent out by the French
government, in the summer of that year, on a scientific expedition to the coast of Sicily, in
company with M. Milne Edwards and M. Blanchard. Many valuable essays and monographs,
resulting from this expedition, have appeared from time to time in the ‘Annales des Sciences
Naturelles/ and have since been published in a collected form. Among these no account of
the researches of M. de Quatrefages on the Phlebenterate Mollusks have yet been given to the
public. We learn, however, from a letter addressed to the Academy of Sciences by that
gentleman, that his researches had tended to confirm the results he had already arrived at.
In June, 1844, he writes that he had had the good fortune to collect twenty-one new species
of these animals, a small number only of which could be included in known genera, and that
he had studied the anatomy of them in great detail. He states that the circulatory apparatus
did not exist, even in a rudimentary state, in the greatest number of the Phlebenterata. That
in the whole of their external characters they resembled the Nudibranchs, but that they were
distinguished from them by the tendency to a bilateral symmetry of the external organs, and
by the repetition of the same organs in longitudinal series; and that in all the function of
digestion was confounded with those of respiration and circulation. +
* It may be necessary to state, that though M. de Quatrefages adopts this opinion, and founds his
generalisations upon it, he afterwards, in the same essay, makes a reservation of the possibility of his
having overlooked the anal opening in some of the species.
t Loc. cit., p. 168.
J f Comptes Rendus/ v. 19, p. 190.