STROPHOMENIA SCANDENS. 107 



The anterior portion of the ventral furrow forms a relatively deep depression 

 (Plate 12, fig. 1) with corrugated walls, the opening of the anterior pedal gland. 

 The gland itself occupies most of the visceral cavity in front of the forward end 

 of the foot (Plate 16, figs. 1, 4). Its cells are of large size relatively, and are 

 charged with a darkly staining secretion that makes its way by slender ducts to 

 the ventral furrow, where each terminates in an intercellular opening. The 

 secretion appears to be viscous, and in one of the specimens carefully dislodged 

 it extended backward for a distance of 22 mm. as a narrow band. 



The cuticle enclosing the body is about 0.2 mm. in thickness and as Plate 16, 

 shows this measurement is very uniform save in the inmiediate neighborhood 

 of the ventral furrow. Imbedded in its substance are, roughly speaking, six 

 to eight layers of spicules, those from the back and sides of the animal being 

 represented (Plate 37, fig. 17). Among these is a much smaller number of radially 

 directed spines that become more minute and more abundant in the neighbor- 

 hood of the foot. 



The hypodermal layer is remarkably sharply defined, and not including 

 the spicule forming elements and those connected with the papillae, consists of 

 cells about twice as high as broad with greatly vacuolated protoplasm and well- 

 defined nuclei occupjdng a more or less central position. Occasionally more 

 slender cells are encountered but these may in reality belong to the papillae. 



The development of the spicule is essentially the same as in P. hawaiiensis 

 (page 28) both as regards the number and arrangement of the operating cells 

 which also retain their connection with the spine as long as it remains in the 

 cuticle. 



As is shown (Plate 32, fig. 3) the papillae are numerous and closely crowded 

 together at the surface. The expanded portion contains not far from twenty 

 nuclei and the stalk from 2-5 ; otherwise there are no especial features of impor- 

 tance. 



The foot arises in the extreme anterior end of the pedal furrow as a well- 

 defined median ridge whose bounding cells are apparently covered with small 

 cilia; but these are usually obscured by the huge cilia of the cells situated lat- 

 erally. In the anterior portions of the ventral furrow the secretion from the 

 anterior gland passes through intercellular openings at all points; more poste- 

 riorly it passes through the foot and the epithelium in immediate contact with 

 it. The secretion of the anterior pedal gland when treated with Delafield's 

 haematoxylin contains one substance which stains almost black and another of 

 light blue tint. These appear to be two distinct secretions, for the dark sub- 



