54 STREPTAXID^E. 



4 Streptaxis is helicoid, Ennea pupoid, and Streptostele achati- 

 noid.' 



" The same author does not describe the animal of Strepto- 

 stele and its anatomy, probably because they are very similar to 

 those of Streptaxis and Ennea. I have examined several species 

 of the latter two genera, and they all agree in the usual bright, 

 yellow or red coloring, extending over the greater part of the 

 body, or being restricted to the head ; the anterior part of the 

 body is always long, extensible, and the posterior short ; the pe- 

 duncles are long, subcylindrical, but the (inferior) tentacles much 

 shorter, exactly as in the Helicidse. The mantle is thickened, 

 generally with a short lobe, or a thickening on each side of the 

 pulmonary orifice. The internal organization closely corresponds 

 with that of the Helicidse, except that the cesophagus is below 

 produced in a tough cylindrical tube, which contains the radula in 

 the form of a narrowly curved sheath ; the tube is attached by a 

 special strong muscle to the retractor of the body. The teeth 

 of the radula are very simple, subconical, pointed, from 40-60 

 in each transverse row. A special jaw is, as far as observations 

 have been made, not developed. 



" All the species which I have observed were found under 

 stones, or trees, and old wood, or under dead leaves and other 

 organic substances. Whether or not the species are carnivorous, 

 as stated by Gray, I have not been able to verify. They are 

 oviparous, like the Bulimi. 



" Considering the form of the teeth, the Streptaxidae are closely 

 allied to the Testacellidae, next to which they are also classed by 

 Gray. Both families agree in the great length of the anterior 

 part of the body and in the more or less secluded habitat. But 

 upon inspection of the anatomy of Testacella, as given by Cuvier, 

 I fail to notice the peculiarity of the long cylindrical tube con- 

 taining the radula." 



Synopsis of Genera. 

 Genus STREPTAXIS, Gray, 1837. 



Shell oval, heliciform, but often oblique, profoundly umbili- 

 cated, ridged, striate above, smooth below; last whorls usually 

 deviating more or less from the original axis ; aperture lunar, 

 with or without teeth ; lip slightly thickened and reflected. 



