GORILLA. 147 



Subgenus STEGODERA v. Martens, 1876. 



Stegodera MTS., Novit. Conch., iv, p. 150. PILSBRY, Man. vi, p. 

 7. Steganodera KOBELT, Illust. Conchylienbuch, p. 236. 



Shell sinistral, disk-shaped, with low spire and open, deep umbil- 

 icus ; solid, opaque, brown. Inner whorls slowly increasing, 

 regular ; latter half of the last whorl distorted, straightened, covering 

 the preceding whorl above. Aperture very oblique, crescentic, tooth- 

 less ; peristorae reflexed ; throat very much contracted. Type P. an- 

 gusticollis, pi. 41, figs. 28, 29. 



Anatomy unknown. A single species is known. 



P. angusticollis v. Mart., vi, 7. Central China. 



Genus CORILLA H. & A. Adams, 1858. 



Gorilla ADS., Gen. Rec. Moll., ii, p. 208. SEMPER, Reisen (2), 

 iii, p. 100 (Anatomy). Atopa ALBERS, Die Hel., p. 90 (in part). 



Shell planorboid, with nearly plane spire and broadly open umbil- 

 icus, the contour subcircular or oblong ; rather solid, striated above, 

 brown or yellow. Whorls 5-5 j, the last deflexed in front. Aper- 

 ture oblique, the lip broadly reflexed or recurved, its ends distant ; 

 parietal wall smooth or armed with a strong entering lamina. Inte- 

 rior of the last whorl either without laminse, or obstructed by a 

 series of blades nearly parallel to the direction of the whorl, but hav- 

 ing no transverse barriers. Type C. erronea Alb., pi. 41, fig. 19. 

 See also pi. 41, figs. 20, 21, 22, C. rivolii Desh. PI. 41, figs. 23, 24, 

 25, C. charpentieri var. hinidunensis). 



Foot (of C. erronea} with undivided sole and without pedal 

 grooves. No mantle lappets. Kidney very short. 



Jaw entirely smooth. Radula with about 79-85 teeth in a trans- 

 verse row. Central tooth not smaller than the laterals, having a 

 single cusp, shorter than the basal-plate. Laterals similar but 

 asymmetrical. Marginals having a large, simple, oblique cusp 

 longer than the square basal-plate (pi. 42, fig. 37, central, 1st and 

 24th teeth of C. erronea). 



Genital system elongated, with no accessory organs on the female 

 side. Spermatheca having a long duct, which branches into a very 

 long flagellum-like diverticu! um, containing a cylindrical spermato- 

 phore, which extended from the end of the diverticulum to the 

 vagina. Penis short, swollen distally, continued in the vas deferens 

 upon which the penis retractor is situated, the distal end of the 



