DISCODORIS VONIHERINGI MAC FARLAND 79 



sule of considerable thickness, intermingled with smooth muscle 

 fibres, surrounds the organ. The vaginal and uterine ducts are 

 united in a common entrance into the spermatotheca. In fig. 71 

 of PI. XIII is shown a reconstruction from sections with the 

 relations of these ducts and of the adjacent organs. The vaginal 

 duct, vag. d., is shown in its proximal portion only, uniting with 

 the uterine duct, u. d., at their common entrance into the sper- 

 matotheca, spth. The uterine duct describes two S shaped loops 

 close together, receives the slender duct of the spermatocyst, spc., 

 and opens into the nidamental gland at its anterior end, and some 

 distance from the anterior margin of the albumen gland. The 

 spermatocyst is of an elongate pear shape, doubled upon itself, 

 its greatest diameter being 0.19 mm., and its length 0.330 mm. 

 It lies immediately in front of and external to the spermatotheca 

 (PI. XIV, figs. 73 and 74, spc.). 



Nidamental-albumen gland complex. The nidamental-albu- 

 men gland is rather small in proportion to the remainder of the 

 anterior genital complex. It is ovoid in outline, the broader end 

 being directed forward and outward. The upper surface is nearly 

 plane, the under surface slightly convex. The surface is marked 

 as usual by parallel convolutions, which are however, not very 

 conspicuous, being quite faint on the central dorsal region 

 occupied by the albumen gland. The duct of the nidamental 

 gland appears upon the ventro-anterior surface (PL XIV, fig. 73, 

 n. d.}, is large, and slightly flattened dorso-ventrally. In cross 

 section (PL XIII, fig. 70) its lumen is seen to be large, the dorsal 

 ventral and anterior walls being thin, and of nearly equal thick- 

 ness. The posterior wall bears two strong parallel longitudinal 

 ridges, d, and v., projecting into the lumen and forming a deep 

 groove between them. At the distal end of the duct these two 

 ridges coalesce, the deep furrow becoming reduced to a shallow 

 groove upon the crest of a single ridge. As the duct approaches 

 the gland proper, this groove widens out, the ventral ridge de- 

 creases and disappears, while the dorsal ridge merges into the 

 roof of the lumen of the gland. 



Upon the external surface there is but little indication of 

 the division into nidamental and albumen glands, such as is 

 usually seen in other Dorididae, but in sections the structural 

 difference is clearly apparent. In PL XIII, fig. 71 the boundary 



