282 Dr. H. A. Nicholson on Bredgings in Lahe Ontario. 



above genera occurred in great abundance in all the dredgings 

 in which a muddy bottom was found in depths of from 2 

 to 20 fathoms, but more abundantly in the smaller depths. 

 The colour varied in different examples from deep blood-red 

 to pink or greenish ; and their semitransparency rendered them 

 very beautiful under the microscope. 



15. Ejiliemeridce. 



Larvae of Ephemerids were found rarely in shallow water 

 to a depth of 2 fathoms. 



MOLLUSCA. 



16. Planorhis trivolvis. Say. 



Very common in shallow water, but not extending beyond 

 a depth of 3 fathoms. 



17. Planorhis jyarvus, Say. 



Very common in shallow water, but not extending beyond 

 a depth of 1 fathom. 



18. Valvata tvicarinaia (?). 



A small spedes of Valvata, apparently referable to the above, 

 occurred abundantly in from 2 to 3 fathoms, ranging, though 

 in much diminished numbers, into depths of from 5 to 8 

 fathoms. 



19. Paludina, sp. 



A large form, nearly allied to P. decisa, Say (perhaps P. 

 impura). This species occurred in a living state and in all 

 stages of growth in from 2 to 3 fathoms on a sandy bottom. 



20. Paludina {Amnicola), sp. 



This is a very minute form which occurred in great plenty, 

 crawling over the stems of Cliara or Anacliaris in from 1 to 

 3 fathoms. 



21. Limnceajugulari^, Say [=L.stagnalis7). 



A large species, occurring in great plenty in shallow water 

 at Toronto Island. It is very nearly allied to L. stagnalis, but 

 it may perhaps be distinct. 



22. Limnaa, sp. 



A smaller and more elongated form, nearly allied to L. 

 columella. Say. 



Eare in from 1 to 2 fathoms. 



