1880.] 



THE GENUS GIRASIA. 293 



from Shillong, all of typical Girasia. These have furnished me 

 with the means of more accurately describing the genus. 



Girasia SHiLLONGENSis, G.-A., J. A. S. B. January 1875, p. 4, 

 pi. n. f. 1, la. / . F . 



The following will be an emended description of the genus:— 

 fehell rudmientary, horny, narrow, elongate, of one simple whorl : 

 colour ohvaceous, apex white, the central portion of the inside of. 



;«? f ll??7T'^ '"'^ ^ milky- white callus. About 1 inch long. 

 (Plate XXIV. fig. 10.) ^ 



Animal slug-hke, long, mantle largely developed; shell and dorsal 

 lobes are united all round ; and the shell is entirely covered by the 

 tormer, with the exception of a narrow area on the posterior left 

 margm. From the anterior right margin of this area a well-marked 

 cicatrical line runs forward to just above the respiratory and anal 

 orihce, and marks the usual division of the shell-lobes in other 

 species into a left (frontal) and right (posterior). The dorsal lobes 

 are divided diagonally forward from the respiratory orifice into a 

 large lett dorsal lobe and (behind and adjacent to the orifices) a 

 smaier right dorsal lobe; on the extreme posterior side a slight 

 beading marks the junction of these lobes with the shell-lobes aboVe. 

 lius portion of the animal is sunk into a deep V-shaped depression 

 in the back, where the dorsal ridge of the foot terminates suddenly. 

 Extremity of the foot truncate, with a large linear mucous gland : 

 the pedal line is very distinct. 



GeniUl aperture near the lower and outer base of the right tentacle. 

 Ihe toot IS divided longitudinally into three subequal median and 

 lateral areas, and is distinctly segmented, the major divisions on the 

 palhal edge of the foot being continued in V-shape from one side to 

 the other, the angle being directed backwards in the spirit-specimen : 

 but they are uo doubt straight when the animal is alive 



Generative organs of G. shillongeusis.-In every way similar to 

 Y-gigas, Us. Ihe ovo-testis consists of five separate bunches or 

 lobes of very minute globular follicles, each lobe having a separate 

 duct leading to the mam hermaphrodite duct ; this gradually widens, 

 and becomes much thickened, with several sharp convolutions j it 

 then suddenly contracts again, leading to the junction of the albu- 

 men-gland. Here a short pear-shaped csecum is conspicuous fonlv 

 seen in one specimen). ^ 



The albumen-gland was not perfect, but appeared as if formed of 

 two lobes (from above specimen). 



The prostate was wide, ribbon-like; the oviduct with three or 

 four great folds, which extend to the posterior termination of the 

 spermatheca, which is not so long as to be infolded by it. The vas 

 deferens is given off a very short distance below the end of sperma- 

 theca, high up the oviduct ; and it extends backwards to near the 

 base of the penis and amatory organ, in a loop, to join the former 

 close behind a crecum-like appendage rounded at the end (the caecum 

 calciferum). The penis is bent on itself, where a long process is 

 given off, to which the retractor muscle is attached. The ama- 



