JAPANESE NUDIBRANCHS. 25 



liver is large and externally yellowish, owing to the follicles of 

 the hermaphrodite gland which form a rather irregularly distribut- 

 ed layer on the upper surface but are present on the lower sur- 

 face only here and there and only in small quantities. The tex- 

 ture of the liver is loose and spongy and the colour inside is 

 mixed, being yellow, brown and black in different parts. It 

 contains several cavities and tubes in which digestion probably 

 tabes place but owing to the imperfect preservation of the organ 

 it is not easy to distinguish between the substance of the liver 

 and the alimentary matter enclosed in it. 



Neither the central nervous system nor the genitalia are 

 very well preserved and the details of their structure are not 

 clear in all points. The ganglia are contained in a stiff capsule 

 which has become fused with the grey and moderately large 

 blood gland. So far as can be jndged, they are much as re- 

 presented by Bergh for Sphaer. lacvis, 1 ^ that is to say fairly 

 distinct from one another and united by short thick connectives. 



Near the point where the hermapherodite duct passes 

 from the surface of the liver to the anterior genital mass is 

 a large curved dilatation but owing to the imperfect preserva- 

 tion of the adjoining parts it is not clear whether it is the am- 

 pulla of the hermaphrodite duct or, at least in part, a prostate. 

 The vas deferens is thin and the glans penis very small. The 

 vaginal duct is long and twisted. The spermatotheca is relatively 

 enormous and spherical measuring about 10 mm. in diameter. 

 The spermatocyst is elongate (about 8 mm. long and 2.5 mm. 

 broad) and constricted at several points. The albumen-mucus 

 gland-complex is large and shows on its underside the coil of a 

 much convoluted tube. 



This specimen raises some difficulties. Firstly the arrangement 

 of the rhinophores is unique : they are retractile not into separate 

 pockets but into a single common pocket. If this structure is 

 regarded as normal, the animal must be made the type of a new 

 genus, if not of a new family. But its other characteristics are 

 those of Sphaerodoris, an exceptionally well marked genus, and it 



1) Mal. Unters. Heft, xvii, pi. Lxxxviii, fig. 3. 



