122 STROPHOMENIA SPINOSA. 



Each consists of a more or less pyriform sac with walls of median thickness to 

 which the spermatozoa are attached in large numbers. In the ventral section, 

 or shell gland, the walls are not so thick as is usual with the majority of Neo- 

 meniina and the central cavity is of greater size (Plate 17, fig. 15). The compo- 

 nent cells are long and contain multitudes of spherical granules staining intensely 

 with haematoxylin. Posteriorly the halves of these glands do not unite with 

 each other or at least not to any marked extent but open separately, though 

 close together (Plate 17, fig. 12), into a shallow depression in the anterior cloacal 

 wall into which the rectum opens also. Immediately ventral to this depression 



there is an outpushing of the wall of the cloaca, that thus holds the same posi- 



* 



tion as the diverticulum in Strophomenia scandens, but it is much more shallow 

 and not so completely closed. The walls of the cloaca lack any folds of definite 

 arrangement, but at three or four points bear slender finger-like outpouchings 

 though without any special modifications to indicate their possible function. 



Strophomenia spinosa, sp. nov. 



Five specimens of this species were taken in southern Japan in the neigh- 

 borhood of Misaki (4 from Sta. 4935-6 and 1 from Sta. 3748) at a depth of 73- 

 200 faths., all were attached to the alcyonarian coral, AcanlhogorgUi japonica. 

 Externally the appearance of these animals differs to a greater degree than in 

 any other species described in the present paper. As may be seen (Plate 1, 

 fig. 3) some (the larger) specimens are almost smooth, while others present such 

 a highly spinose appearance that at the outset they were supposed to be distinct 

 species.' Here and there sections show that some of the great spines ordinarily 

 protruding almost at a right angle above the cuticle have been withdrawn so 

 that their bases invade the territory of the somatic musculature (Plate 33, fig. 7); 

 and it appears probable that this species is able to protrude or withtlraw these 

 spines and possibly adapt itself to a shifting habitat as Echinominia coralliophila 

 is known to do. The length of the body is approximately 28 mm. with an 

 average diameter of 1 mm. Both ends of the body are similar, the anterior 

 being distinguished usually by its slightly greater thickness. The color is gray- 

 ish white. 



The cuticle, 0.1 nun. in thickness (Plate 33, fig. 7), is in reality rather scant 



' It is possible that these differences in external appearances are of specific value, and that we are 



dealing with two distinct forms. Plate 34, figs. 8, 9, 10, .show differences in the radulae, and in the 



smooth," large form there are thirty-one seminal receptacles while there are twelve in the smaller, 



spiny type. Nicrstr:isz ('02), however, claims that these last named organs vary considerably in 



number in the same species. Additional material is necessary to settle the question. 



