560 PROCEEDINGS OF THE NATIONAL MUSEUM vol. io8 



very large tooth covered with a cuticularized coat ; at its base a small 

 tooth is seen on each side but no other teeth were evident in the ante- 

 rior part of the sac. At about the middle there is another similar large 

 tooth with cuticularized surface and distal to this the liunen is lined 

 with small teeth that increase in size distally to the beginning of the 

 male antrum proper. The antrum is a tubular exit lined by a tall 

 epithelium; its anterior wall forms a pair of glandular pouches that 

 receive eosinophilous secretion. Prostatic duct and anterior part of 

 the cirrus sac are surrounded by a so-called space that is filled with a 

 vague bluish material in stained sections. It seems to be present in 

 aU members of the genus. 



The female gonopore is well separated from the male pore. It 

 leads into a short tubular female antrum from which the wider vagina 

 with much folded walls ascends. Characteristic of the present species 

 are two strongly marked cement pockets of the vagina, an anterior and 

 a posterior one. Each receives a great cloud of cement glands. The 

 posterior pocket is the larger of the two, although this is not evident 

 in the median section, since it expands laterally, and receives the 

 greater mass of cement glands. Dorsal to the entrance of these cement 

 pockets, the vagina receives the copulatory bursa from in front, then 

 proceeds dorsally and curves posteriorly above the posterior cement 

 mass. At this point it receives separately the two oviducts (not shown 

 in the jEigure), then descends as the duct of Lang's vesicle and opens 

 into the relatively short Lang's vesicle. The female tract of these 

 parts is lined by a cuboidal to taU epithelium and is rather muscular 

 at first; the muscular investment declines towards Lang's vesicle 

 which has scarcely any muscular fibers outside the epithelium. 



The copulatory bursa, not further illustrated, is an extremely mus- 

 cular pyriform sac that extends anteriorly from the vagina along the 

 right side of the male apparatus to the level of the right spermiducal 

 bulb. The immensely thick muscular wall of a web of muscle fibers 

 gradually diminishes in thickness towards the blind end of the bursa 

 and concomitantly the liunen, which does not seem to be lined by a 

 definite epithelium, enlarges. At the proximal end of the bursa, the 

 wall is relatively thin, although still muscular, and the lumen quite 

 large. The waU is everywhere greatly folded into the lumen. The 

 interior, especially proximally, contains a great mass, presumably 

 sperm, but so dense this cannot be determined certainly. 



Differential diagnosis: This is the ninth species to be assigned 

 to the genus and the question of the validity of these species remains 

 baffling. The matter of validity was discussed by Kato (1936), 

 Prudhoe (1945), and H}Tnan (1953a); Prudhoe, especially, was in- 

 clined to reduce the number of species by throwing most into synon- 

 ymy with P. oligoglena. But it now appears to me that insufficient 



