Miscellaneous. 135 
analogy with that of the Brachiopod, always excepting the position 
of the valves. Now this is also easy to be brought under the gene- 
ral plan of the Anodonta, if we suppose the two lateral lobes of the 
mantle to be united above the mouth and below the anus, and imagine 
that about the middle of its length an emargination is formed which 
may advance as far as the hinge; for then the two halves of the 
mantle are no longer lateral, but dorsal and abdominal, and the shell 
reproduces the pattern upon which it models itself. 
The modifications undergone by the muscles are the consequences 
of the changes of arrangement which have taken place in the shell; 
they cannot invalidate the zoological approximation which I am en- 
deavouring to establish. Do we not, for example, find an Ascidian 
(Chevreulius) presenting symmetrical muscles analogous to those of 
the Terebratulz, and this merely because its tunic has become bivalve, 
and without one being able to remove it from the group to which it 
belongs ? 
If we now compare the Polyzoan or Bryozoan with the Brachiopod, 
we find some external resemblances, but profound differences of 
greater importance. No doubt the Bryozoan often presents an organ 
in the form of a horseshoe, placed close to the mouth, and which 
may be compared to the arms of the Brachiopods; but this is not a 
sufficient feature of resemblance to bring together animals so differ- 
ent. If we look at the nervous system, we shall soon be convinced. 
Hitherto the Molluscoida have presented only a very simple ner- 
vous ganglion, without an cesophageal collar, and without any very 
evident double symmetry ; consequently they are more distant from 
the Brachiopoda than the latter from the Lamellibranchiata. 
Thus the investigation of the nervous system legitimates the ap- 
proximation which we are seeking to establish, and does not justify 
that which the English authors have attempted ; but it leads us also 
to recognize the necessity of making a distinct group for the Brachi- 
opods, which are much rather degraded Acephala than elevated 
Molluscoida. 
These zoological relationships are by no means invalidated by an 
organic peculiarity as curious as unexpected. Professor Huxley was 
the first to demonstrate the non-perforation of the anal extremity of 
the intestine in the Terebratulee, and I have myself confirmed this 
observation in several other genera and species; this arrangement 
forms a very remarkable exception among the Mollusca, and appears 
to be especially proper to the Articulate Brachiopods, which really 
represent Calenterate Mollusca. 
The preceding general observations constitute a résumé of minute 
and detailed investigations undertaken in 1858 in Corsica, and in 1862 
in Algeria, upon thegenera Megerlia, Terebratulina, Thecidia, Argi- 
ope, and Crania, which inhabit the Mediterranean, and were all ob- 
served living on the spots which they inhabit.—Comptes Rendus, 
November 6, 1865, pp. 800-803. 
