STROPHOMENIA TRIANGULARIS. 125 



other species described in the present paper. On the side represented (Plate 9, 

 fig. 4), there are thirty-one and as may be seen these are of various sizes, ranging 

 in diameter from 0.2 mm. to one fourth this size. On the other hand it is to be 

 noted that another specimen from the same alcyonarian colony has but twelve 

 receptacles (Plate 12, fig. 3). The cells composing these organs are unusually 

 large and in many situations are greatly vacuolated. This latter peculiarity, 

 however, may be due to the fixing fluid since at all points where spermatozoa are 

 attached to the walls the cells are more dense though of the same height as the 

 others. The stalks connecting the receptacles are comparatively short, lined 

 with low cubical cells and usually open separately into the coelomoduct (Plate 17, 

 fig. 5). 



The shell gland is nowise peculiar except that it is of somewhat greater 

 diameter than usual and more in-egular in outline. Its cells are columnar and 

 are partially filled with a darkly staining secretion that has escaped into the 

 lumen in considerable quantities. It may be added that in specimens of this 

 type ova occur in the pericardial cavity and the breeding season is therefore at 

 its height. As usual the halves of the shell gland are not clearly united, but with 

 the rectum open together into the cloaca. 



Strophomenia triangularis, sp. nov. 



Five specimens of this species were taken off the southern end of Honshu 

 Island, Japan, two from Station 3716, two from Station 4935 and one from 

 Station 4936 at depths of 65-125, 103 and 103 faths. respectively. The length 

 of all is approximately 12 mm. with a width of 1.6 mm. The body is flattened 

 ventrally, and the presence of a low broad keel extending along the dorsal side 

 of the body and terminating about 1 mm. from each extremity, gives the animal 

 a triangular appearance in cross section. Every specimen is coiled in a close 

 spiral (Plate 1, fig. 5) around the stem of an alcyonarian coral, Calicogorgia sp. 



The color of preserved material is a dull grayish yellow. The opening 

 into the atrium is subterminal, and is clearly separated from the ventral furrow. 

 The foot, a single fold, extends from the hinder wall of the anterior pedal gland 

 outlet to the cloaca. A dorso-terminal sense organ is present. The cuticle on 

 the back and dorso-lateral surfaces measures 0.108 mm. in depth to twice this 

 thickness on the ventral surface. In decalcified material the papillae extend 

 more or less above the surface of the cuticle (Plate 33, fig. 1), but in a natural 

 state these are so surrounded or overlaid by spicules that they are usually in- 

 visible in surface view. The outer enlarged portion of each papilla is relatively 



