150 STYLODONTA. 



Jaw stout, arched, with no ribs, but having a few coarse, broad 

 vertical wrinkles (Studeriana), or weak, fine and close strise (uni- 

 dentata). 



Radula large, composed of nearly straight transverse rows of 

 teeth. Central teeth with one broadly rounded cusp shorter than the 

 basal plates; laterals similar, but the cusp longer and inclined; 

 marginals having an inclined broad mesoconeand developing a small 

 ectocone (pi. 48, fig. 9, S. studeriana). 



In studeriana the radula measures 12J x 5 mill., and the formula 

 of teeth is 47.22.1.22.47. In unidentata the radula measures 10 x 4 

 mill., and the formula is 43.17.1.17.43. 



Genitalia imperfectly known by Viguier's figures and description 

 (see pi. 50, figs. 6, 7, 9, S. studeriana). The figures show the male 

 system below, female system above. The penis is large. Vagina 

 long, bearing a long duct ending in an oval spermatheca. Uterus 

 large, containing two yoang shells, which are enclosed in membran- 

 ous pouches, and attached to them by a sort of umbilical cord 

 formed of the pouch wall (pi. 50, fig. 9). The uterus and pouches 

 are filled with a glairy substance, probably nutritive, and secreted 

 by the albumen gland. The organs above the uterus are un- 

 known. 



Large, solid Helices, inhabiting the Seychelles Islands. They are 

 viviparous, bringing forth one or two young at a time. They live 

 on bushesor climbing vines,feed upon green leaves, and sestivate under 

 the soil or in rock crevices. Dufo supposed that only the lighter 

 colored individuals were females, but his observations lack anatomi- 

 cal confirmation. The shells are very dull colored for arboreal forms. 



Besides the viviparous reproduction, and the large size of the young 

 at birth, these species are peculiar in having a small ectocone de- 

 veloped on the outer marginal teeth, the dentition being otherwise 

 like that of Acavus. The large size of embryonal shell, the ribless 

 jaw, and the peculiar teeth, all forbid the association of these shells 

 with the genus Camcena. S. studeriana is found upon the island of 

 Praslin only. It lives upon the leaves and trunk of the Coco-de-mer 

 tree. S. unidentata occurs on Mahe, Felicite, Silhouette and Curi- 

 euse Islands. The young shells are acutely keeled, as in Pyrochilus, 

 not rounded as in Helicophanta, Acavus, Panda, etc. 



S. uuidentata Chemn., vi, 86. S. unidentata Chemn. 

 microdonta Dh. v. exanthematica v. Mts. 



uniplicata Hartm. v. militaris Pfr. 



normalis Martens. v. globata v. Mts. 



