452 SUMMARY OF CURRENT RESEARCHES RELATING TO 



occupies segment XI, on the ventral side of which there is a muscular 

 sucker, with the openings of a pair of sperm-ducts at its edges. Four 

 pairs of ovaries, situated in segments ix and x, lie freely in the coelom, 

 and show large ova with much yolk. The spermothecas open in seg- 

 ment in ; the sperm-sacs occur in segments viii and x ; there are large 

 sperm-funnels in x ; the sperm-ducts are long and coiled. 



Earthworm with Caudal Bifurcation.* — L. Bordas gives a careful 

 description of the internal structure as well as of the external appearance 

 of a specimen of Lumbricus here idem which resembled a Y reversed. 

 The anterior portion was 9*5 cm. in length with 120 segments; the 

 right posterior portion in a line with the anterior portion was 38 mm. 

 in length with 70 segments ; the left posterior portion or lateral bud 

 was 27 mm. in length with 45 segments. Each posterior portion had an 

 anus and a gut. On the dorsal surface, at the bifurcation, there was a 

 median smooth area, corresponding to eight segments. On the ventral 

 surface, in the same position, the segmentation was not interrupted. 

 The branch showed a normal nerve-cord, attached by a narrow isthmus 

 to the main cord, and there were the three main blood-vessels — dorsal, 

 ventral, and sub-neural. 



Clare Island Annelids.f — R. Southern reports on the Archiannelids 

 and Polychsetes found in the Clare Island area. There were three 

 Archiannelids, Nerilla antennata, Polygordius lacteus, and P. appendi- 

 culatus, the species of Polygordms being new to the British fauna. The 

 list of Polychgetes comprises 249 species and two varieties, which is by far 

 the largest list as yet recorded from any limited area. Thirty-six species 

 have not been recorded previously from the British Marine Area, and 

 seventy-seven are recorded from Irish waters for the first time. There 

 are sixteen new species and two new genera — Prsegeria (very closely 

 related to Pisione), and Thelepides (near Thelepus). 



Nematohelminthes. 



Intra-uterine Development of Spermatozoa in Ascaris. :): — D. 

 Tretjakoff has followed up his earlier work on spermatogenesis in 

 Ascaris megalocephala by a study of the intra-uterine formation of 

 sperms in Ascaris lumbricoides. In contrast to A. Mayer and other 

 observers he believes that the change from the spermatid stage to the 

 mature spermatozoon is gone through after copulation, and not within 

 the male organs, or suddenly at the moment of copulation. His observa- 

 tions lead him to believe that pairing in Ascarids only takes place when 

 the previous provision of spermatozoa is quite exhausted. No more ova 

 are then produced in the ovaries, and the uterus also becomes free from 

 ova. Under ordinary circumstances, the expulsion of ova from the 

 vagina is due to contraction of the muscular layer of the uterus and 

 vagina, but the author believes that, at this complete clearing out of 



* Bull. Soc. Zool. Prance, xxxix. (1914) pp. 252-60 (5 figs.). 

 t Proc. R. Irish Acad., xxxi. (1914) Clare Island Survey, part 47, pp. 1-160 

 (14 pis.). 



% Arch. Mikr. Anat., lxxxv. (1914) pp. 135-203 (3 pis. and 1 fig.). 



