64 Lake Maxinkuckee, Physical and Biological Survey 



They are dark brown in color with very faint rays. The species 

 appears to be rare in the Tippecanoe River at Delong. One ex- 

 ample was obtained there, which is somewhat shorter and stouter 

 than those of the lake, and not so badly stained ; it shows faint 

 rays posteriorly. The Lost Lake shells are somewhat larger than 

 those found at the other lakes. No young were found, the smallest 

 shell obtained being a half-grown example. One gravid specimen 

 was found at Lost Lake Sept. 7, 1908. The marsupium closely 

 resembles that of L. iris, being a kidney-shaped mass filling the 

 hinder portion of the outer gill, this mass being marked into seg- 

 ments by rather deep radiating furrows. The very edge of the mar- 

 supium is white beyond the dusky submarginal area, the white 

 making a chain-like area at the edge of the gill. Like L. iris, this 

 species has a tendency to form pearls, but they are too small to be 

 of any value. 



Food of individuals: — The following is the result of the exam- 

 ination of the contents of the intestines of L. subrostrata from Lost 

 Lake at various dates. 



Sample 22, August 20, 1908. A small amount of flocculent 

 bluish-gray material. 



Peridinium tabulatum abundant; Microcystis aeruginosa abund- 

 ant; Anuraea cochlearis; Pediastrum boryanum; Diatoms — Sy- 

 nedra, Cymbella cymbiformis. 



Sample 23, August 20, 1908. A very small amount of floccu- 

 lent grayish material. 



Peridinium tabulatum a few; Microcystis aeruginosa a little; 

 Pediastrum boryanum; Cosmarium, Tetraedron minimum, Scene- 

 desmus, Euglyphia alveolata; Peridinium, a small, sharp-spined 

 form. Diatoms make up the greater part, including Cymbella 

 cymbiformis, Navicula, Fragilaria, Coscinodiscus, and Epithemia. 



Sample 24, September 7. A large amount of material, black 

 mud below, greenish flocculent material above. The upper por- 

 tion contains chiefly Botryococcus braunii and Microcystis aerug- 

 inosa. Bottom portion — Microcystis aeruginosa common; Botnj- 

 ococcus braunii; Peridinium tabulatum, Peridinium, a small spined 

 species; Scenedesmus, frequent. Staurastrum, Pediastrum duplex; 

 Coelastrum a few; Anuraea cochlearis, Tetraedron, Docidium, 

 Coelosphaerium kuetzingianum, sponge spicule, Lyngbya aestuarii. 

 Diatoms, — Synedra, Navicula, Gomphonema, etc. 



