202 MR T. J. EVANS ON 



The Reproductive System. (Fig. 12.) 



No adequate description or figure of this system in a Bathydoris has hitherto been 

 given, but both Eliot and Bergh give a somewhat hesitating impression that it is 

 constructed on the Dorid plan. Since the universal triauly of known Dorids is one of 

 their most striking characteristics, it is essential that on such a critical point our 

 knowledge should be clear and definite. 



The hermaphrodite gonad (h.g.) lies posteriorly below the kidney and above the liver 

 within the arc made by the intestine. It is a yellowish, bi-convex lenticular body, 

 truncated in front and with a minutely lobulated surface. The specimen was captured 

 at the stage of male activity in the protandric cycle, since the male acini and ducts 

 are full of sperms, while the eggs are small and lightly yolked. Its blood supply is 

 an extension of the renal arterial system, branches from which pass through the lower 

 wall of the kidney into its substance. 



The common hermaphrodite duct (c.h.d.) leaves the gonad as a single slender 

 tube. It is ampullated (amp.), as usual in Nudibranchs, but its extreme length escaped 

 previous notice. After a short, slender portion beyond the ampulla, it divides into 

 two tubes, the vas deferens (v.d.) and the oviduct (o.d.). The vas deferens is a 

 comparatively short, coiled tube, expanded by the glands in its walls into a prostate 

 for nearly the whole of its length. It enters the penis sac (p.s.) some distance 

 from the end and runs a straight course to the tip of the everted penis imbedded 

 in loose connective tissue and muscle fibres. The mode of extroversion of the 

 penis, deducible from dissection of the everted organ, is represented in the section- 

 diagrams (fig. 11, a and b), the dotted area representing loose fibrous tissue the 

 perfusion of which with blood from the hsemocoele causes the extroversion. The penis 

 is seen to be a partial introvert, since the end is retracted into the sac unchanged. 

 This terminal portion (p.) presents a remarkable appearance on account of the sucker- 

 like pits covering one side of it. It is possible that the pits, under control of the 

 blood-pressure in the penis, really act as suckers on the smooth surface of the female 

 atrial wall. 



The oviduct soon enters the massive mucus-albumen gland complex (m.g. and a.g.), 

 the structure of which could not be investigated on account of its stony hardness. The 

 albumen gland could be recognised on the upper surface by its yellowish-brown colour 

 and its granular consistency. The coils of the mucus gland end distally as the broad 

 tube which opens into the female atrium. The atrium is turned out as in copulation : 

 the first part of it has a highly crinkled surface, but inside this arise two leaf-like lips 

 (a.l.), or folds of its surface, which between them enclose the entrance (f.o.) into the 

 female channel. These valvular lips appear to be a characteristic feature of Bathydoris, 

 because they are also partially shown in surface view in B. clavigera by Thiele. 

 Within the valve on the posterior wall of the channel opens the vagina (vg.), which 

 consists of a stout tube ending blindly in a globular recurved bursa copulatrix (b.c). 



