234 A NATURALIST IN THE GREAT LAKES REGION 



contectoides is a large thin shell, banded or otherwise brightly 

 colored. Here too are such clams as Alasmodonta marginata 

 (Fig. 181) and Lampsilis luteola (Fig. 180). Some fairly good- 

 sized fish come into the shallow area to lay their eggs in the sand 

 of the bottom, such as the black bass, pumpkin seed (Fig. 188), 

 bluegill (Fig. 187), perch, crappie (Fig. 438). The fish may 

 often be seen, on careful approach, swimming in the neighbor- 

 hood of the nest, especially the male that does guard duty until 

 the young are hatched. In the very shallow water the blob or 

 miller's thumb, one of the sculpins (Fig. 325); the blunt-nosed 

 minnow (Fig. 429), straw-colored minnow (Fig. 436), and the 



FIG. 325. Blob, miller's thumb, or sculpin, Coitus ictalops. After Forbes 



Johnny darter (Fig. 429) are found and probably breed here. 

 The crayfish, Cambarus mrilis, is common, hiding under stones 

 and logs. 



The waters of the lake are the habitat of many algae that 

 grow in profusion, Cladophora, Spirogyra, Oedigonium, Hydrodic- 

 ton, etc. They usually go under the common names of pond 

 scums or water silk. Nearer shore there is an abundant floating 

 vegetation consisting of such Hepaticae as Riccia, Ricciocarpus 

 and flowering plants like the duckweeds. Riccia appears like a 

 thick green leaf (really a thallus) about as large as your finger 

 nail. There are short rootlike structures (rhizpids) given off 

 from its under side. It floats on the shallow water or lies on the 

 soft mud. Duckweed is also a floating plant with one or two 

 tiny leaves and, for a short time in spring, a tiny blossom. 



