274 



purpureo-violaceis ; epidermide nigro-virescente vestita, in latere 

 antico late sulcata, strils remotis; umbonibus prominentibus, erosis, 

 antice inclinatis ; cardine lato, crasso, valde obliquo, inaequaliter tri- 

 dentato, dente mediano bifido ; dentibus latcralibus subaequalibus, 

 serrulatis ; ligamento crasso. 



Long. 3^ ; lat. 3 ; diam. 1| poll. 



Habitat, Nova Caledonia. Collect. Cuming et Prime. 



CoRBicuLA DUCALis. Prime. 



Cyrena fluminea. Mousson, Moll. Java. 87, pi. xv. f. 3. 



C. testa ovato-trigona, oblique inaequilaterali, tumidS, utrSque 

 extremitate gequaliter obtusa, epidermide olivaceo-flava, nitente 

 vestita, transverse sulcata, striis valde distantibus ; umbonibus inflatis 

 obtusis, erosis ; valvis crassis, intus albis, ad dentes laterales violaceis ; 

 cardine angusto ; dentibus cardinalibus tribus, mediano crassiore, 

 postice angusto, lateralibus angustis, serrulatis. 



Long. l| ; lat. W ; diam. ^ poll. 



Habitat, Java. Collect. Prime. 



Lateral Symmetry in Brachiopoda. By N. S. Shaler. 



In tbe course of some examinations into the nature and value of 

 the type characters of the Mollusca, I have been led to certain con- 

 clusions, which I hope will tend in some degree to remove the doubt 

 which has been freely expressed by Malacologists of high authority, 

 as to those features which are now generally accepted as character- 

 istic of the type. 



Since the time of Cuvier's division of the animal kingdom, the t\^e 

 of Mollusca has been usually accepted by naturalists, and though 

 there has been some diiference of opinion concerning what groujDS 

 are to be admitted into the category, and much doubt as to the more 

 important divisions within the type, still the existence of the group 

 has never been questioned. Yet while naturalists have with una- 

 nimity recognized the distinction exhibited in the Mollusca, and 

 expressed such distinction in their systems of classification, they have 

 always been much at variance as to what the characters of the type 

 are. Even Cuvier, though he gives many good reasons for distin- 

 guishing the MoUusks from the other branches, fails to give us any 

 hint as to what the fundamental ideas of the type are, and though he 

 presents to us extensive details of the points of difference between 

 members of the type of Mollusca and representatives of the other 

 branches, he does not seem to have apprehended those fundamental 

 thoughts of the type to which these structural points stand in a 

 secondary relation. I think that it is in the Essay on Classification 

 that we find for the first time a clear statement of the idea which 



