Lake Maxinkuckee, Physical and Biological Survey 57 



and with the epidermis rather green than brown, and in having 

 the shell usually somewhat thinner. Some of the shells near the 

 outlet of Lost Lake are exceedingly thin, some of them so much 

 so that ordinary print can easily be read through them; they are 

 so fragile that it is almost impossible to keep them. 



Of the collection from Lake Maxinkuckee, mostly from Long 

 Point, 26 examples were carefully compared. The smallest meas- 

 ured 68 mm. long, 38 mm. high and 24.6 mm. in diameter, and the 

 largest 93.5 mm. long, 50 mm. high and 37 mm. in diameter. 

 Among variant forms was one female, gravid when collected, 

 which was unusually elongate, its measurements being 86 mm. 

 long, 43.5 mm. high and 32.5 mm. in diameter. In outline this 

 shell closely resembled Anodontoides f erussacianus subcylin- 

 draceus. 



Some of the larger specimens are rather humped and arcuate, 

 the ventral margin of one being somewhat concave. This is a 

 variation which is quite likely to occur in old shells of any species. 



Although gravid Anodontas were found rather frequently dur- 

 ing the late autumn, no infected fishes were seen, and no young 

 were found. 



The Anodontas of the lake are fairly free from parasites, a few 

 Atax and Cotylaspis and occasionally a few distomids on the mantle 

 next to the umbonal cavity being the only ones present in any 

 numbers. In some of the other lakes the Anodontas were very 

 badly infested; a colony found in one of the Twin Lakes being 

 infested to a remarkable degree by a distomid which formed cysts 

 in the margin of the mantle. 



Food and Parasites of various examples: — The following is the 

 result of the examination of various examples of Anodontas from 

 the lake. 



Sample 10. Vial containing intestinal contents of Anodonta 

 grandis footiana, Lost Lake, Sept. 7, 1908. The vial contains a 

 considerable amount of material (in formalin) which was sepa- 

 rated into black fine mud below and fine fiocculent light green 

 above. Upper portion — Microcystis aeruginosa most common; 

 Peridinium tabulatum some; Pediastrum boryanum; Melosira 

 crenulata, a few filaments ; Coekistrum microporum, Botryococcus 

 braunii and Scenedesnius. Bottom layer — Lyngbya aestuarii, 

 Microcystis aeruginosa very common; Peridinium tabulation, 

 Anuraea cochlearis, Cymbella cymbiformis and Navicula. 



Sample 11. Food of Anodonta grandis footiana, Lake Maxin- 

 kuckee, near Norris Inlet, Aug. 20, 1908. A good mass of fioc- 

 culent fine green material ; no mud. 



