78 OPISTHOBRANCHIATA OF BRAZIL 



the organ. The gland cells are large and clear, with large, 

 deeply staining nuclei, the reticular cytoplasm being distended 

 with a clear albuminous secretion, staining with difficulty. The 

 poor fixation of the single specimen available precluded any 

 satisfactory cytological study of the gland. 



Vas deferens and penis. From the distal end of the prostate 

 gland passes the vas deferens (PI. XIV, figs. 73, 74, v. d.} a slender 

 tube, ca. 3.0 mm. long, which courses with but few loopings 

 outward and forward, terminating in the penis into which it rather 

 suddenly dilates (PI. XIV, figs. 73, 74, />.). It is lined with a 

 single layer of slender columnar epithelium, surrounded by a thin 

 layer of smooth muscle cells and a connective tissue adventitia. 

 Toward the distal end the muscular elements become much in- 

 creased, the wall of the praeputium being made up almost entirely 

 of them. The penis was strongly retracted and curved upon itself, 

 as was also the whole organ. It is bluntly cylindrical in shape, 

 slightly tapering and is entirely destitute of any armature. 



Vagina. The vagina (PI. XIV, figs. 73, 74, vag.) is small 

 and conical in general form, its length in the slightly contracted 

 condition being i.o mm., with a maximum diameter of 0.5 mm. 

 Its slender duct (PI. XIV, fig. 74, vag. d.) passes directly 

 inward to the central region of the dorsal face of the anterior 

 genital complex where it opens into the spermatotheca (PI. XIV, 

 fig. 74, spth.). In cross section about midway of its length it 

 has a diameter of 0.097 mm -> f which 0.052 mm. is occupied by 

 the lumen. The lining is formed by a single layer of cubical 

 epithelium bearing long cilia, in the distal portion elevated into 

 long ridges, which become lower and disappear in the proximal 

 portion. The muscular coat is strongly developed, and consists 

 of a circular and a longitudinal layer, enclosed externally by a 

 connective tissue adventitia. 



Spermatotheca and spermatocyst. The oblong flattened 

 spermatotheca lies in the center of the dorsal face of the anterior 

 genital complex (PI. XIV, figs. 73, 74, spth.). It is of a light 

 amber color, is slightly flattened dorso-ventrally, measuring 0.435 

 mm. in its antero-posterior diameter by 0.315 mm. dorso-ventrally, 

 with an extreme length of 0.46 mm. It is lined by a high colum- 

 nar epithelium, apparently ciliated, but the preservation of the 

 specimen renders this point uncertain. A connective tissue cap- 



