192 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 15 



The copulatory region was removed and sectioned sagittally. A 

 median sagittal view of the copulatory apparatuses is given in fig. 10, 

 but as the bursa is laterally placed, it does not appear in this section. 

 As shown in fig. 8, the sperm ducts approach the prostatic vesicle from 

 the sides, acquire muscular walls, and become spermiducal bulbs. These 

 unite in the median line ventral to the attached end of the prostatic 

 vesicle to form a common duct that enters the prostatic duct (fig. 10). 

 The prostatic vesicle is a rounded body with a muscular wall and glandu- 

 lar interior; the latter is supplied, at least in part, by extracapsular 

 glands, the necks of which pass through the proximal wall of the vesicle. 

 The prostatic vesicle gives off a wide duct that, after receiving the com- 

 mon sperm duct, proceeds along the center of the cirrus sac. The latter 

 is bound within the same muscular sheath as the prostatic vesicle and its 

 interior is composed of loose tissue which contains diagonal muscle bands 

 that converge towards its tip. The lumen of the cirrus sac begins about 

 half way along the organ and is lined by a few scattered spines and 

 occupied by the proximal part of a very long cirrus papilla. This con- 

 tinues from the ejaculatory duct and occupies the proximal half of the 

 cirrus sac as a long slender projection, scantily armed with spines on its 

 outer surface. The tip of the cirrus papilla extends almost to the female 

 gonopore. 



The female gonopore lies not far behind the male pore and leads into 

 a female antrum that, contrary to the usual condition in the Planoceridae, 

 lacks special muscularization. From it, the vagina continues with a for- 

 ward slant through the mass of cement glands, then curves dorsally and 

 backwards, where it presents a papillate lining that receives the cement 

 glands. The vagina then becomes muscular, acquiring a thick coat of 

 circular fibers ; it curves downward behind the mass of cement glands 

 and, after receiving the common oviduct and giving off the duct of the 

 bursa, continues with a backward bend as the very short duct of Lang's 

 vesicle. This opens at once into the very long Lang's vesicle. 



These latter parts of the female apparatus are best seen on a para- 

 sagittal section, since the copulatory bursa is situated well to one side. 

 Such a section is depicted in fig. 11, which shows the muscular vagina 

 descending behind the mass of cement glands and giving off a broad 

 muscular duct to the copulatory bursa. The latter is an elongated sac 

 whose histology is difficult to determine because the interior stains 

 heavily. There appears to be no definite lumen and the interior seems to 

 consist of a complicated web of muscle columns. The function of this 

 bursa is problematical. It seems improbable that it can actually be a 

 copulatory bursa, that is, a recipient of sperm at copulation, for it lacks 



