214 NEOMENIA VERRILLI. 



Each penial spicule sheath and the included spine are of unusual length 

 and girth, and with the accompanying muscles form a very conspicuous element 

 of the accessory reproductive apparatus. In addition to these elements there 

 exists a trough-like guide or groove (Plate 4, fig. 8) in which the spiciile rests. 

 As in the case of the spine this guide appears to be cuticular in character, but 

 whether in life this serves as a matrix for calcium salts it is impossible to state 

 at present. Both of the structures are secreted by numerous slender cells, 

 clear and well-defined at the distal extremity of the sheath, but growing indis- 

 tinguishable near the free opposite end. 



The external sheath is composed largely of connective tissue to which the 

 retractor and protractor muscles are attached. The first named are of larger 

 size and are united with the sheath in the neighborhood of its distal extremity. 

 On the other hand they become inserted chiefly in the cuticular trough though 

 small slips extend to the spine that thus is possessed of a certain amount of 

 independent action. The protractors attaching to the spine are comparatively 

 thin and delicate, and, so far as may be judged from sections, are attached 

 both to the grooved guide and to the sheath. Another protractor, of much 

 larger size, is inserted in the grooved plate near its outer end, and extending 

 in a postero-ventral direction fuses with the somatic musculature lateral to 

 the posterior termination of the foot. 



In addition to these elements the spicular apparatus comprises- a pair of 

 highly developed glands (pgl) that in the present instance are fully as large 

 as the shell gland. Each of these is placed somewhat above and to the inside 

 of the ventral limbs of the coelomoducts or shell gland (Plate 4, fig. 1), and 

 presents the appearance of an inflated sac ellipsoid in form. Internally well- 

 defined septa spring from the walls, and in the anterior end of the organ these 

 become so united that they form a number of diverticula communicating with 

 the main cavity of the gland. The cells of the epithelial lining are more or 

 less goblet-Uke in shape, and distally contain vacuoles in which are occasional 

 globules of some secretion. 



In the neighborhood of the free extremity of the retracted spine a duct 

 opens into the surrounding space, and on the other hand passes laterally then 

 dorsally and toward the mid hne to enter the mass of connective tissue ventral 

 to the shell gland. In this position, close to the gland just described, it becomes 

 lost to view owing to the mutilation of the specimen. Two possibiUties present 

 themselves; either it opens into the shell gland or into this large, overlying 

 gland. The former course appears unUkely, especially in view of the fact 



