76 Bulletin Wisconsin Natural History Society. [Vol. 9, Nos. 1-2. 



Green lake is the deepest inland lake of Wisconsin, having a 

 maximum depth of 237 feet, and measuring over 100 feet deep 

 over the greater part of its area. Its waters are remarkably clear. 

 It harbors "a true abyssal fauna, organisms which can exist only 

 in the peculiar environment of uniform low temperature and 

 little or no light." (Marsh, Bulletin No. 12, Wisconsin Geological 

 and Natural History Survey). Prominent in this fauna are the 

 two remarkable Crustacea, Pontoporeia Hoyi and Mysis relicta. 

 It has also long been known that a cisco (Leitcichthys) forms a 

 part of this fauna. 



It seems to have been common practice among ichthyologists to 

 consider this form conspecific with Leitcichthys (Argyrosomus) 

 nigripinnis, as found in Lake Michigan. An examination of our 

 specimens, however, makes it very plain that this can not be true. 

 Jordan and Evermann have recently made a careful review of 

 the salmonoid fishes of the Great Lakes. (Bulletin U. S. Bureau 

 of Fisheries, Vol. 29, pp. 1-41, Plates I-VII). A detailed com- 

 parison of the Green lake specimens with the species therein 

 mentioned, shows it to be very evidently distinct. It shows 

 undoubted relationship to the two Lake Superior deep water 

 forms, supernas and zenithieus, and especially to the latter. But it 

 is clearly distinct from both by its smaller eye. From supernas it 

 is further to be distinguished by its more slender caudal peduncle, 

 its non-projecting lower jaw, and its shorter gill rakers. The 

 number of scales along the lateral line is distinctly smaller than 

 in zenithieus. 



I am indebted especially to Mr. A. E. Gurdy of Green Lake, 

 Wisconsin, for information concerning the habits of this form. 

 It is very markedly a deep water fish, practically never appearing 

 near the surface except to spawn. Only rarely do they appear 

 near the surface in spring (June) and then probably while pur- 

 suing some swarm of aquatic insect larvae. 



Some of the specimens in our collection have the stomachs 

 crammed with food, and in every case this proved to consist 

 entirely of Pontoporeia Hoyi. In winter, however, they are found 

 frequently with remains of small fishes. 



The spawning season comes in November, being at its height 

 about the middle of the month. Local fishermen generally believe 

 that the spawning takes place at a depth of about seventy feet, on 

 marly bottom, but this is somewhat doubtful. 



