296 Mr. R. Etheridge, Jun., on the Gasteropoda 



type which, exists between the two, so far as outward form is 

 concerned. It is the 



Conch. (Helicites) auricularis, Martin, Petr. Derb. 1809, t. 40. figs. 3, 4. 

 Pileopsis neritoides, Phillips, loc. cit. 



Capulus neritoides, De Koninck, Anirnaux Fossiles, p. 334 ; Morris, Cat. 

 Brit. Foss. 1854, 2nd ed. p. 239. 



Pileopsis vetusta, Sow. (Phillips, p. 224, t. 14. fig. 19). 



This specimen is in a bad state of preservation, but it has 

 an obliquely placed and spirally inrolled apex after the P. 

 neritoides type. Prof, de Koninck has united it with the 

 latter, and Prof. M'Coy with Martin's P. auricularis along 

 with others. These authors are doubtless correct in this ; it 

 is not the true P. vetusta, Sowerby. 



Pileopsis angustus, Phillips (p. 224, t. 14. fig. 20) . 



A small, almost entirely decorticated shell with an oblique 

 spiral apex after the type of P. neritoides, with which it has 

 been united by Prof. M'Coy as a synonym of P. auricularis, 

 Martin. I quite fail to see how it can be separated, except as 

 a variety with a less sinuated and more regular shape. It 

 is the 



Pileopsis angustus, Phillips, loc. cit. 



Acroculia angustus, M'Ooy, Synop. Carb. Foss. Ireland, 1844, p. 44. 



Capidus auricularis, M'Ooy, Brit. Pal. Foss. 1853, fasc. iii. p. 523. 



Capulus angustus, Morris, Cat. Brit. Foss. 1854, 2nd ed. p. 239. 



On the Shells called Pileopsis by Phillips. — Under what 

 name should these shells be known ? The generic names 

 Capulus, Montfort, Platyceras, Conrad, Acroculia, Phillips, 

 and Pileopsis, Lamarck, have been used for them ; and the 

 question to which of these should they be referred turns more 

 or less upon that of their internal structure, more particularly 

 of the muscular system. There appears to be little question 

 of the identity of Capulus and Pileopsis on the one hand, and 

 of Platyceras and Acroculia on the other ; whilst Capulus is 

 as much anterior in date to Pileopsis as Platyceras is to Acro- 

 culia ; we have therefore a choice between Capulus and 

 Platyceras. 



In Capulus the muscular impression is horseshoe-shaped, 

 discontinued or open towards the anterior or front of the shell. 

 This may be satisfactorily seen in C. hungaricus or any of 

 the larger recent species. So far as I am aware, the form of the 

 scar in Platyceras, Conrad (= Acroculia, Phillips), was little 

 known until figured by Messrs. Meek and Worthen, who have 

 shown that the scars in P. infundibulum, M. & W., are horse- 

 shoe-shaped, with lateral dilatations, and situated on the pos- 



