33 



and then eggs ; fecundation takes place, and a new generation 

 is brought forth/' Here there appears to be a single tube which 

 performs both functions, and of course there is no male outlet. 

 If there be no mistake here, and the worm itself should resemble 

 in form Filaria Medinensis, it will afford strong grounds for 

 assuming that the same kind of generative process takes place 

 in the latter. But, without desire to impugn in the least M. 

 Schneider's assertion, I would observe that this takes place in 

 all the free microscopic Filaridse which I have described (the 

 type of which in Urolabes palustris is figured*), with this excep- 

 tion, that the store of undeveloped spermatozoa which is always 

 present at the upper end of the oviduct, close to the opening of 

 the ovisac, has been introduced by the male ; hence it is pos- 

 sible that a female Filaria in this state might be mistaken for a 

 hermaphrodite of the description mentioned by M. Schneider f. 

 Bombay, August 1860. 



EXPLANATION OF PLATE L A. figs. 1^. 



Fig. \. Filaria Musccb, n. sp. ; natural size. 



Fi(j. 2. The same, magnified : a, oesophagus ; b, intestine ; e, intestinal 



sheath ; d, liver ; e, rectum and anus. 

 Fiff, 3. The same, more magnified, in three portions : a, two upper papillae ; 



b, small part of oesophagus ; c, large ditto ; d, oesophageal sheath ; 



e e e, dorsal vessel; /, ovary charged with nucleated cells; 



g, vulva ; h, testicle charged with nucleated cells ; i, penis ; 



k, anterior extremity of liver ; I, anterior extremity of intestine ; 



m, posterior end of liver; n, intestine and intestinal sheath; 



0, rectum and anus ; p, spinous extremity of tail. 

 Fiy. 4. Spermatic cells, containing each a single spermatozoon : a, front 



view, showing striated triangular form of spermatozoon based 



u])on granular mucus ; b, the same, lateral view ; c, fully deve- 

 loped (?) spermatozoon. 



VII. — Remarks upon some points in the Economy of the Nudi- 

 branchiate Mollusca. By Cuthbert Collingwood, M.B., 

 F.L.S. &c.t 



[Plate IV.] 



The following observations were suggested by a small Nudi- 

 branch which was kindly sent me by a correspondent residing in 

 Glasgow, Mr. Robertson, on the ^5th of October last. This 

 minute but beautiful little animal was dredged on a frond of 

 Laminaria saccharina in 8 or 10 fathoms water, from a sheltered 



* Annals, loc. cit. pi. 2. tig. 13. 

 t Auuals, vol. v. p. 506, June 1860. 



X Communicated by the author, having been read before a Meeting 

 of the Liverpool Ray Club. 



Ann. 6f Ma(/. N. Hist. Ser. 3. Vol. vii. 



