Dr. F. E. Beddaid on the Genus Tiicliodiikis. 233 



Whether they extend further than this I do not know. They 

 contained hu-ge ripe ova with the usual abundant yoljj. 



The sperm-ducts are in segments IX. ^ X., XI., and open on 

 eacli side by the atrium on to the tenth segment. The 

 funnels are in the ninth segment and the tenth, and are much 

 as figured and described by Clapar^de in this, and, by him 

 and others, in other Lumbriculids allied to Tnchodrilus. The 

 funnels were, as is usual, conspicuous owing to the bundle of 

 spermatozoa caught up by the ciliated mouth of each. The 

 main part of tlie posterior pair of s])ei-m-ducts forms a coil in 

 the eleventh segment close to the anterior wall of that segment. 

 I did not observe the actual openings of the sperm-ducts into 

 the atrium with absolute certainty. The funnels, instead of 

 being flattened over the septum and plate-shaped, are cup- 

 shaped, as Hesse (quoted below) figures in Lumhriculus *. 



The atrium is generally as recorded by Claparbde f. It is 

 noteworthy for the very thick circular muscle-layer figured by 

 that author, and subsequently by Ditlevsen \ and Piguet §. 

 Its duct to the exterior is narrow and projects as a penis into 

 an ingrowth of the epidermis, forming a small circular cavit}-. 

 This is not indicated by Clapai^de. As I point out later, the 

 characters of the atrium may distinguish this genus from 

 Phreatothrix. Hesse ||,. and, latei', Alrazek ^ have given 

 figures of the atrium of Lwnbriculus, and the first-named has 

 compared it with that of ClaparedUla, Tthynchehnis^ Stylo- 

 drilus, and Trichodrilus, remarking that tliese forms have 

 always glandular cells outside of the atrium, but never 

 muscle-layers as in Lumhriculuf^. This in spite of Clapar^de's 

 figure referred to by him. However, Hesse appears to be 

 correct in his statements of the other genera mentioned in 

 his list, admittedly taken from the writings of others *''^. It 



* Or perhaps they would be better described as funnel-shaped. Miss 

 Dixon {Tubifex, Liv. Mar. Biol. Comm. Memoirs, xxiii., London, 1915) 

 remarks (p. f)S, cf. pi. iv. figs. 17, 18) that the funnels of Tubifex are 

 cup-shaped in the more immature worm, and more expanded later. 



t Mom. Soc. Phys. Geneve, t. c, pi. iii. fig. 6. Claparedo does not 

 indicate the lining epithelium of the atrium. 



^ " Studien an Oligochaten," Zeitsohr. wiss. Zool. Bd. Ixxvii. 1904, 

 p. 441, Tuf. xvii. fig. 49. 



§ Rev. Zool. Suisse, t. c. woodcut, p. 141 . 



II " L)ie Geschlechtsorgane von Liimh-icuhis vanec/atus, Grube," 

 Zsitschr. wis?. Zool. Bd. Iviii. 1894, p. 355 (also published as Bd. i. no. 1 

 of ' Tiibinger Zoologis^che Arbeiteu '). 



II " Die Geschleclitsverhaltnisse und die Geschlechtsorgane von Lum- 

 briculiis variegatuf, Gr.," Zool. Jahib. Hd. xxxiii. 1900, p. 381. 



** More lately Michaelsen has figured (Bull. Ac. St. Petersb., Sept. 1901, 

 pi. xi. fig. 19) a circular muscle-layer in Uhyiichelmis brachycej^hala. 



