THE CYCLOPHORID LAJSTD MOLLUSKS OF AJNIEIRIOA 169 



The type was collected by Germain at Santa Cruz de la Sierra, 

 Bolivia. It measures: Height, 16 mm.; greater diameter, 21 mm. 



We have not seen this species. The above is a translation of 

 Ancey's description, to which he adds: "Its prominent lirae, dull 

 colour and deciduous epidermis are its most striking characters." 



Although quite different, it belongs to the group of G. cumvngi 

 (Sowerby). 



Genus CYRTOTOMA Miirch 



1852. Cyrtotoma Moech, Catalogus conchyliorum . . Comes de Yoldi, vol. 1, p. 40. 



Araphicyclotine shells of helicoid outline ; the sculpture consists of 

 hairlike riblets; the outer peristome is expanded and reflected. The 

 peristome on the parietal wall may be almost entire or vary from this 

 to deeply notched. The operculum is corneous with central nucleus, 

 and the outer edge of the whorls is upturned. 



Type: Cyrtotoma mexicanum (Menke). 



Distribution : Southeastern Mexico. 



The radula formula of C. walkeri (H. B. Baker) is 3: 3: 3: 2, and 

 the jaw has a median projection. The verge is situated on the right 

 side of the neck and is traversed by a seminal groove only. It does 

 not have a terminal appendage. 



KEY TO THE SPECIES OF CYRTOTOMA 



Subsutural thread present. 



Parietal notch conspicuous. 



Parietal notch broad and U-shaped. 



Peristome decidedly double avus 



Peristome not decidedly double salleanum 



Parietal notch V-shaped ignotum 



Parietal notch obsolete fischeri 



Subsutural thread absent. 



Parietal notch much deeper than wide palmeri 



Parietal notch not deeper than wide. 



Peristome strongly flaringly expanded mexicanum 



Peristome not strongly flaringly expanded. 



Greater diameter more than 20 mm goldmani 



Greater diameter less than 16 mm walkeri 



CYRTOTOMA AVUS, new species 



Plate 22, Figubes 22-24 



Shell large, depressed helicoid, covered by a golden-brown perio- 

 stracum, below which the last whorl of the shell is soiled white and 

 the rest rosy tinged. The whorls are marked by coarse, retractively 

 curved incremental lines ; which on the last whorl almost form riblets. 

 There is a spiral thread immediately below the rather deeply chan- 

 neled suture. Periphery well rounded. Base strongly rounded, 



