204 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



The anterior prostate, in XVII, is double, as regards both 

 the glandular and the muscular part. A single large pros- 

 tate opens with the sperm-ducts in the equator of somite 

 XVIII. With this prostate opens also a pair of penial setae 

 exactly similar to those in XVII and XIX. The other side 

 of the worm does not exhibit these peculiarities. 



Detailed Description. 



Owing to the indifferent state of preservation of the single 

 specimen, but few details can be given. The spermathecae 

 are very large and have the form of elongated sacs without 

 diverticles. The upper end of the sac is somewhat wider 

 than the lower half near the pore. The walls are very 

 thick. The upper, larger chamber is lined by very long 

 columnar epithelium. The lower part exhibits a very 

 peculiar structure. The lumen is narrow and the walls are 

 enormously thick. These walls are made up of large, 

 globular, glandular cells of various sizes. The cells are 

 separated into groups by trabecula, thus having the appear- 

 ance of closely packed composite glands. Around this 

 glandular part of the prostate is seen the usual muscular 

 layer. The epithelial cells of the upper chamber are 

 arranged in groups like villi and are fully as large as the 

 epithelial cells of the intestine. The pores of the sperma- 

 thecae are postseptal, though opening into the angle of the 

 intersegmental grooves. 



There is a pair of racemose sperm-sacs in XII, but instead 

 of projecting from the septum they are seen to grow around 

 the hearts in that somite, the connection with the septum 

 probably having been separated. 



The glandular part of the f restate is by far the longest, 

 extending to the dorsal part of the somite. The muscular 

 duct is very short and narrow, extending only a little way 

 above the body-wall. Outwardly the glandular part is 

 entire, but sections show it to be composed of numerous 

 separate though closely packed lobes of glandular cells. In 

 the part nearest the lower lumen two distinct layers of cells 

 can be distinguished, but in the upper part there is only one. 



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