82 collinge: non-opkrculate land and freshwater molluscs. 



in an ovoid-sac, the receptaculum seminis (PI. iv, fig. 24, r.x.). The 

 penis is short, \vith an epiphallus of great length, variously folded and 

 twisted upon itself, it penetrates the distal wall of the penis and 

 terminates in a short, bluntly ending, fleshy papilla (PI. v, fig. 26, p.p.); 

 beyond the epiphallus is a long flagellum whose distal portion is 

 densely coiled. Internally the wall of the penis is thrown into a 

 series of thick, longitudinal, muscular folds, with short cross con- 

 necting folds (PI. V, fig. 26). The retractor muscle of the penis is 

 short, and inserted on the right- side, at the proximal end of the 

 epiphallus. The vas deferens leaves the latter organ as a narrow tube, 

 and passing forward along its walls, it bends back again over the region 

 of the vagina and joins the common duct, which is long, and richly 

 folded. The albumen gland is long and narrow. The hermaphrodite 

 duct short and convoluted. 



In the second specimen (PI. iv, fig. 25) the chief differences are, 

 that the vagina is shorter and S-shaped, the receptacular duct longer and 

 narrower, the epiphallus and flagellum both shorter, and the retractor 

 muscle of the penis longer. 



llie Free Muscles (PI. v, fig. 27). — The buccal retractor consists of a 

 series of short muscular bands inserted on the vetnral side of the 

 buccal cavity, and two rather longer bands, one being inserted on each 

 lateral wall of the buccal cavity. All these fuse immediately behind 

 the buccal cavity, and pass backward as a single band. The ten- 

 tacular and pedal retractors are similar on both sides. The superior 

 and inferior tentaculars first join, forming a stout band with which the 

 pedal unites a little more posteriorly. The columellar muscle is short 

 and narrow, and twisted twice. 



The Pallial Region (PI. v, fig. 28). — The kidney is unusually large, 

 measuring 51 "5 millim. in length and 5*5 millim. in breadth. The 

 ureter passes off from the anterior border, and in the region just in 

 front of the pericardium it passes across the dorsal side of the kidney, 

 continuing its course backward on the opposite side, to the posterior 

 end of the lung, where it bends forward again and runs along the side 

 of the rectum. In a sinistral example of this species the ureter does 

 not cross over the kidney. The measurements of the different organs 

 in the two specimens were as follows : 



Lung. Kidney. Pericardium. 



Dextral 65 "5 51 "5 10 millim. long. 



Sinistral 80 58 8 „ ,, 



Hapalus, Albcrs. 



Hapalus jousseaumei, de Morgan. 



