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 Terebratulse, and this merely because its tunic has become bivalve, 

 and without one being able to remove it from the group to which it 

 belongs 1 



If we now compare the Polyzoan or Bryozoan with the Brachiopod; 

 we find some external resemblances, but profound diflFerences 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 oesophageal 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 Terebratulse, and I have myself confirmed this 

 observation in several other genera and species ; this arrangement 

 forms a very remarkable exception among the MoUusca, and appears 

 to be especially proper to the Articulate Brachiopods, which really 

 represent Coelenterate MoUusca. 



The preceding general observations constitute a resumi of minute 

 and detailed investigations undertaken in 1858 in Corsica, and in 1862 

 in Algeria, upon the.genera Megerlia, Terebratulina, Thecidia, Argi- 

 ope, and Crania, which inhabit the Mediterranean, and were all ob- 

 served living on the spots which they inhabit. — Comptes Rendu4, 

 November 6, 1865, pp. 800-803. 



