I I STACEA. 68 



PI.AXORBUS IMBKICATCS. Plato XI. Figs. 7, 8, 9, 10. 



iMnmrter of the shell a line ; volution* tlirec, with transverse spinon- 

 ridges at intervals formed around the tortion of the epidermis. The 

 interval* between the ridge* are hollow. When free of impurity, the 

 >lell is grey or of a reddi-li tinge. Animal a Limax. Ten turn la two, 

 almoct cylindrical, obtuse, incurved during progression. A black eye 

 tenants the front of the head at the base of each. Sole oval. Colour of 

 the animal dark grey. It feeds on vegetable substaiKvs, including tin- 

 bark of beech and other tree* lying in ponds and canal*. 



Thin creature spawns in February and in May. The spawn consist* 

 of very minute spots, generally containing a single embryo, and Home- 

 times two. I have not at any time observed more. The spawn is im- 



-'. unites when affixed to the side of a glass vessel. 

 . -imens have survived above eighteen months in confinement. 



PLATE XI. 



Km. 7. Plaiurbit 



8. The Mine, enlarged. 



9. Spawn. 



10. The nine, enlarged. 



VAI.TATA OBTOSA. Plate XL Figs. 11, 12, 13, 14, 15, 10, 17, 18, 

 19,20,21,22,23, 1M 



Strictly speaking, this is not one of the logarithmic curved, flattened 

 >h.'lL ; it more resemble* the Helixes of our field* and gardens. 



Diameter of the shell a quarter of an inch, height nearly as much. 

 Volutes four, rising gradually in conical arrangement above each utin 

 and concave below. Orifices circular, closed by an operculum. Animal 

 a Limax. Length above a quarter of an inch ; head cylindrical, distinct. 

 Sole, with a broadened shoulder recurving to each side, like some of the 

 Kolides in the Doris tribes. Shortened extremity obtuse. A branchial 



