18Sf?.] 



ON A WORM OF THE GENUS ^OLOSOMA. 



213 



p. 307). The so-called genus Callocardia, founded upon this species, 

 represented hitherto only by a single valve in the British iMuseum, 

 and supposed to belong' to "the family Isocardiidse, certainly belongs 

 to the Veneridse, and camiot with any propriety be separated from the 

 section Caryatis of the ancient Lamarckian genus Cijtherea. This 

 being tlie case it becomes necessary to change the specific name given 

 to Mr. Adams's type, the name Cytherea giUtata being preoccupied 

 by Romer. I therefore propose for it the name of 



Cytherea (Caryatis) isocardia. 



The shell is described by Mr. Edgar A. Smith in his report of the 

 LameUibranchiata of the '' Challenger,' from the before-mentioned 

 single valve. There is little to add to that description. Tlie hinge 

 is almost identical with that of C hangerfordi, the shell is more 

 inflated and the umbones more distant. Of the two specimens, 

 one is beautifully painted with squarish light brown markings, and 

 the other has only angular markings and spots about the dorsal 



EXPLANATION OF PLATE XL 



Fig. 1-.3. Cypraa hungerfvrdl, p. 208. 



4. Cytherea {Caryatis) hunger- 



fordi, p. 212. 



5. Trochus 2>onsonhyi, p. 209. 

 6-7. cxquiiitits (magnified), 



p. 210. 

 8-9. ColumheIlafilbyi,^.2Q8. 



10. Engina anyulata, p. 210. 



11. Coralliophila turrita, p. 209. 



Fig. 12. 

 13. 

 14. 

 15. 

 1(5. 

 17 



Lima smithi, p. 207. 

 Helix boxalli, p. 211. 



ct/closfremoides, p. 212. 



Mallefia angidata, p. 208. 



Plcurutoma bulowi, p. 211. 

 fidtoni, p. 210. 



18. TurriteUa rohusta, ]i. 211. 



19. Cassis ceniica, p. 211. 



20. Lima conccntrica, p. 207. 



3. Observations upou an Annelid of the Genus jEolosonia. 

 By Frank E. Beddard, M.A., F.R.S.E., Prosector to 

 the Society, Lecturer on Biology at Guy's Hospital. 



[Eeceived February 15, 1888.] 

 (Plate XII.) 



In looking over a sample of water from a small tank belonging to 

 Mr. Bartlett, Mr. F. W. Headley noted, and directed my attention 

 to, a small worm chnging to a fragment of duckweed. This I 

 recognized as an example of the freshwater Annelid JEolosoina. 

 I obtained further supplies of water from the same tank which was 

 found to be swarming with this little worm. The animals, however, 

 were only rarely observed swimming freely in the clear water, but a 

 large number could be at once brought into view by simply stirring 

 up the duckweed with the dipping-tube ; if left to themselves, they 

 ra[)idly made their way up to the surface of the water where the 

 duckweed was floaluig, and disappeared from view. Individuals 



