Dr. F. E. Beddard on the Genus Trichodrilus. 229 



These vessels, he states, join the dorsal vessel with the ventral. 

 Vejdovsky doubts the continuity of these transverse vessels 

 with the ventral vessel, and regards them as probably ending 

 blindly like the contractile appendages of Lumbriculus and 

 many other Lumbriculids. I could myself see nothing of the 

 kind in the live specimens examined by myself. It is true 

 that the chloragogen layer upon the dorsal vessel and the gut 

 is thick and opaque; but at least during the systole and 

 diastole of the dorsal vessel the inflow of the blood into that 

 vessel must have been visible were such vessels present. On 

 the other hand, I was able to note the generally diffused red 

 colour of the wall of the intestine, which is doubtless to be 

 regarded as the expression of a blood-sinus round the gut. 

 This is to be contrasted with the network of non-contractile 

 capillaries which I found upon the wall of the gut in Phrea- 

 tothrix cantabrigiensis, in which species also the blind 

 appendages of the dorsal vessel were not to be seen. These 

 species, however, are not unique among the Lumbriculidse, by 

 reason of the absence of these undoubtedly highly charac- 

 teristic vascular appendages. Were they so, I should have 

 asserted their absence in the worms just mentioned with 

 greater hesitation. 



In Claparedilla asiatica *, a genus later transferred to the 

 older genus Bythonomus of Grube by the same author f, 

 Michaelsen has gone at some length into the proof of the 

 absence of csecal vascular appendages of the dorsal blood- 

 vessel, and has convinced himself that they are actually 

 absent. With less certainty, perhaps, Michaelsen has also 

 come to the conclusion that while some species of his genus 

 Lamprodrilus have these appendages others have them not J. 

 That I myself was not able to detect them in transverse or 

 longitudinal sections of preserved examples of Trichodrilus 

 would of itself be dangerous evidence perhaps ; I dwell 

 rather upon their invisibility in the living worm with con- 

 tracting dorsal vessel. I have not myself examined these 

 vessels in any Lumbriculid, where they undoubtedly occur, 

 by the section method §. But Michaelsen records a good 

 many such observations, and is thus able to speak more 

 positively upon their absence in others. In both Stylodrilus 

 and Styhscolex there is a similar absence of blind appendages. 



* " Oligochseten der zoologischen Museen zu St. Petersburg und Kiew," 

 Bull. Ac. Imp. Sciences St. Petersb. (5) xv. 1901, p. 181. 



t " Die Oligochseten des Baikal-Sees," in Wiss. Ergebn. Zool. Exp. 

 Baikal-See, Kiew und Berlin, 1905. 



X Ibid. p. 49 for L. pygmaus and p. 51 for L. isoporus &c. 



§ Except in Sutroa (Trans. R. Soc. Ed. 1892, p. 195) ; but have no 

 note on the subject to refer to. 



