106 MARINE AND FISHERIES 



5 GEORGE v., A. 1915 

 Genus Anodontoides. 



Represented by a single species. 



Anodontoides ferussacianus, Lea. Plentiful in shallow sand channels and also 

 in muddy places. Compared with A. grandis is smaller and much more elongated. 

 Fine radiating sculpture at posterior of beak in addition to the five or six concen- 

 tric doubly looped ridges. Color brown, tinged with green anteriorly and below 

 and rusty brown posteriorly and above. (PI. XII, Fig., 27) . 



Genus Unio. 



Of this genus also only a single species occurs. 



Unio complanatus, Solander. Very abundant in sand channels and along 

 muddy or sandy shores of the inner islands or bays. Shells dark brown, no rays, 

 beaks eroded, placed well forward, height behind beaks not greatly exceeding that 

 in front, anterior end rounded, posterior tends to be angled. Ventral margin and 

 hinge margin nearly straight, margin behind hinge curved. Teeth, both cardinal 

 and lateral, single in right and double in left valve. Very variable, shells, narrow 

 or broad, light or heavy; nacre white or purple. In old shells ventral margin tends 

 to become emarginate. (PI. XII, Fig. 29). 



Family sphaeriidae. 



There are of this family, in this region, six species belonging to the two genera, 

 Sphaerium and Pisidium. 



Genera Sphaerium. 



Five of the six species mentioned above belong to this genus. 



Sphaerium simile, Say, occurs abundantly, buried in the sand on the slopes of 

 deep pools in sandy channels; occurs also in the mud of sheltered bays. The 

 largest of the family in this district. Beaks nearer anterior end of shell, inflated, 

 closely approximated, beaks marked with coarse lines, lines of growth heavy, 

 regular. Color brown or yellow, often brown with yellow border. Hinge line 

 curved. Hinge slight. Varies in color. Young usually yellow, adult usually dark. 

 Young thin, adult somewhat inflated. (Pi. I, Fig. 11). 



Sphaerium striatinum, Lamarck. Abundant in sand banks in channels and in 

 mud in sheltered bays. Shell somewhat inequilateral, beaks full, separated, lines 

 of growth coarse with finer lines between. Beak sculpture not uniform, numerous 

 regular coarse lines, few coarse lines irregularly placed or beak smooth. Shell thin, 

 nacre bluish white with purple bands or patches. 



Sphaerium rhomboideum, Say. Sand banks and muddy bays. Shell equi- 

 lateral. Umbones depressed, approximated, marked by fine lines, lines of growth 

 rather fine, regular; anterior slightly truncated, posterior somewhat angled below. 

 Dark brown, narrow yellow border around margin; nacre bluish white. (PL X, 

 Fig. 12). 



