232 Dr. F. E. Beddard on the Genus Trichodfilus. 



reduced in size, though still plain enough for the purposes of 

 identification as such. 



The numbers and position of the spermathecse were those 

 of Triclwdrilus as opposed to Phreatothrix, for there were two 

 distinct pairs of the spermathecse of quite equal size in 

 segments XI., XII,, instead of two spermathecse only — those 

 of the anterior pair, — together with a smaller pair belonging 

 to posterior set. But it will be remembered that In my 

 species Phreatothrix cantabrigzensis there was no trace of the 

 second (posterior) pair. Doubtless this is not a strong reason 

 for separating the two supposed genera ; but it is a reason, 

 among others, for proving the difference between the two 

 subterranean worms of East Anglia, which would certainly 

 have been expected to be of the same species. 



The sperniathecce, like those of other Lumbrieulids, consist 

 of a thin-walled sac and a thicker-walled duct. The sac has 

 a lining composed of a single layer of cells. This is covered 

 by a delicate peritoneal layer also one cell thick. I could 

 detect no muscle-fibres between the two layers. The general 

 form of the sac is oval, but varies a little. There is nothing 

 in any way remarkable about their form. Spermatozoa, not 

 aggregated into bundles, were to be seen lying loosely but 

 closely in the sacs. The ducts of the organs are very narrow 

 and fully one-third of the length of the sac or rather more,, 

 and either straight or twisted in their course to the exterior. 

 The muscular wall of circular fibres is relatively thick. The 

 openings are posterior in the eleventh and twelfth segments 

 on a level with, and occupying a similar position to, the atrial 

 pores, or very nearly so. 



There are two pairs of testes in segments IX., X., close to 

 the nerve-cord. They are flattened dorso-ventrally and not 

 very wide. They extend through perhaps a length of half 

 the segment. 



The ovaries correspond exactly in position to the testes and 

 lie in segment xi. They are, however, different in shape, 

 being pear-shaped and much larger. 



I have found sperm-sacs in one or other of the two specimens 

 which I have investigated by longitudinal sections in segments 

 X.-XIII. inclusive. There are also sperm-sacs in segment 

 VIII., and, like those of Aurantina aurantiaca * , are attached 

 to the wail dividing vili./ix., and depend into segment viil. 



The egg-sacs are in segments Xin., XIV., XV., XVI. 



* Pierantoni, "Oligocbeti del Fiume Sarno," Archiv. Zoolog. Napoli, 

 1905, vol. ii. fasc. 2, p. 232, tav. xiv. figs. 4, t>, ssp. 



