New Land Shells from Costa Rica. 257 



XXIII. — On the Jaw and Lingual Dentition of certain Costa 



Rica Land Shells collected oy Dr. William M. Gabb. 



BY W. G. BINNEY. 



(with PLATE XI.) 

 Bead December 23d, 1878. 



Among the specimens of land shells collected in Costa Rica 

 by the lamented Br. Gabb, were several preserved in spirits. 

 These were submitted to me by him. I have examined the jaw 

 and lingual dentition, and here offer the results of my exam- 

 ination. The original figures of the living animals, as drawn 

 by Dr. Gabb, are also given, and his notes incorporated in the 

 text. It will be seen that Dr. Gabb discovered two new 



genera. 



Velifera*, n. g. 



Animal f (pi- xi, fig- A), heliciform, blunt before, tapering behind ; man- 

 tle subcentral, thin, furnished with one or ■ more J accessory processes 

 which cover most of the shell : respiratory, anal, and generative orifices, — ? ; 

 a distinct locomotive disk : longitudinal furrows above the margin of the 

 foot, meeting over a simple, longitudinal mucus-pore (pi. xi, fig. D. ) 



Shell (pi. xi, fig. B) imperforate, globose, very thin, polished; whorls few 

 the last very large, scarcely falling at the aperture: aperture slightly oblique, 

 large: peristome acute. 



• Jaw with smooth anterior surface and beak-like projection to the cutting 

 edge. 



Lingual membrane (pi. xi, fig. C) with the general arrangement of Zon- 

 ites : the first laterals have an inner side cutting point : marginals aculeate, 

 with side spur. 



Although this animal does not combine the characters of 

 any described genus, it is related to several by its separate 

 characters. It has the caudal mucus-pore, and the jaw, of 

 Zonites; but differs in having an appendiculate mantle. In 



* Velum, a covering, a vail ; fero. 



j- Animal heliciforme, antice obtusum, postice attenuatum, pallium tenue, 

 subcentrale, appendiculatum, testam velans; apertura respiratoria, analis, 

 et genitalis, — ?; discus gressorius distinctus; porus mucosus caudalis. 



Testa imperforata, globosa, tenuis, nitens, paucispira, anfr. ultimus 

 globosus; peristoma acutum, 



% As Dr. Gabb's figure gives the left of the animal, it is impossible to 

 describe these processes correctly, 



