280 Dr. H. A. Nicholson oh Dredgings in Lake Ontario. 



Clepsine ; but, so far as I am aware, attention has not been 

 otherwise drawn to it (American Journ. Science and Arts, 

 vol. iii. Feb. 1872). I have also observed it in a species of 

 Clepsine from Lake Ontario, and shall describe it more fully 

 upon a future occasion. 



Common in from 1 to 3 fathoms. • 



3. Clepsine, sp. 



A small leech, about | inch in length in extension. The 

 body flattened, with broad, transparent margins exhibiting 

 numerous lateral papillee. Back and belly, with exception of 

 the transparent borders above alluded to, of a dirty greenish 

 brown. The anterior end of the body is attenuated ; the pos- 

 terior extremity wide and flattened out ; and when irritated, it 

 has the habit of rolling up into a ball. This species, also, 

 carries its young attached to the posterior portion of its ventral 

 surface, in a small rounded bunch. 



Common in from 1 to 3 fathoms. 



4. Clepsine (?). 



A small undetermined leech, of a worm-like shape and a 

 red colour. Length when contracted about | inch, in exten- 

 sion about 1 inch. Instead of remaining quietly attached 

 to some foreign body, like the preceding species, this leech 

 swims actively through the water by a serpentine bending 

 of the body. 



Rare in 3 fathoms. 



5. S(e7iurisj sp. 



A large OligochEetous Annelide, about 2 inches in length, 

 of a red colour, with an iridescent blue intestinal streak. 



A single individual was obtained in 3 fathoms, on a sandy 

 bottom. 



6. Sceiiuris or CMrodrillus, sp. 



A small and very slender form, varying in length from 

 J inch up to 1 inch, and of a red colour. These minute 

 Annelides occurred in extraordinary numbers at all depths of 

 the lake from 3 up to 45 fathoms ; but they were much more 

 abundant at the smaller than at the greater depths. They 

 were uniformly found wherever the bottom consisted of a fine 

 tenacious clayey mud. 



Crustacea. 



7. Gammarus, sp. 



A small freshwater shrimp, varying in length from ^ to $ 

 inch, and of a greenish-brown colour during life, with a dark 



