1867.] DR. J. E. GRAY ON CATILLl S 993 



belly, inner side and front and back part of tbe limbs, and tbe side 

 and under surface of the tail yellow. 



Hab. Eastern Peru, near Xeberos (E. Bartlett ; Brit. Mas.). 



The black part of tlie hands and legs near tlie yellow colour is 

 varied with more or less abundant yellow hairs. 



I have named this fine species after Mr. A. D. Bartlett, the Super- 

 intendent of the Society's Gardens, and his son Edward (who dis- 

 covered it). 



8. Notes ou Catillus, Humplu'ey, or Navicella, Lamarck, 

 with Descriptions of Two New Genera. By Dr. J. E, 

 Gray, F.R.S., V.P.Z.S., F.L S., &c. 



Linnaeus and Bory St. Vincent referred this shell to the genus 

 Patella. Chemnitz properly removed it to Nerita ; and De Koissy 

 considered it a species of Crepidula of Lamarck. Other authors 

 have regarded it as the type of a genus. Thus Humphrey called it 

 Catillus, Schumacher Sandalium, Ferussac Sejjtaria, and Lamarck 

 Navicella. 



Lamarck and Ferussac divided their shells into two or three spe- 

 cies : — the one having an oval, convex, more or less thick, solid shell, 

 and more or less acute s])ire, which was called N. elliptica, Lamk., 

 and Septaria borbonica, Ferussac ; the other a narrow oblong thin 

 shell, more or less rounded at each end, called N. lineata, Lamk., 

 and Septaria navicida, Ferus.>;ac. These two species are the types 

 of two forms, each of which has been divided into several species. 

 The forms are generally distinctly marked ; but there are a few spe- 

 cimens which seem to be more or less completely intermediate be- 

 tween them. 



Mr. Lovell Reeve, in his ' Conchologica Iconica,' has divided the 

 specimens into thirty-three species, or pseudo-species (most, if not 

 all, of them figured from specimens in Mr. Cuming's collection), 

 separated from each other by slight modifications in the form of the 

 shell and of the inner lip, and in the distinctness and distribution 

 of the colours. I think I may state, without any fear of contradic- 

 tion, that it is utterly impossible to distinguish a large proportion of 

 the species proposed in this work by the specific characters, or even 

 by the figures given. Such characters and figures are merely to 

 satisfy the rule that a species is not established unless it is charac- 

 terized ; but surely that implies that it shall be characterized so that 

 it may be distinguished ; otherwise, as in this case, it is a mere pre- 

 tence, and therefore best avoided. 



Mr. Reeve does not give figures of or describe the operculum of 

 any of the species, which is the less excusable as Mr. Cuming's 

 collection, from which the figures are taken, contains the opercula 

 of more than a third of the shells which he has regarded as sj)eciea ; 

 and the opercula of the different specimens ])resent such niodifica- 



