. Fresh-water biology. Freshwater biology. 698 FRESH-WATER BIOLOGY 39 (25) Cervical sinus present. No crest 40 40 (45) Valves transversely striated. Post-abdomen broad, with indenta- tion in which anus opens. Simocephalus Schoedler 1858 . 41 Body large and heavy; shell thick. Head and rostrum small. Valves large, somewhat quadrate, with rounded angles and sometimes a posterior spine; marked with oblique striae, anastomosing irregularly and with cross-connections. Two abdominal processes developed, placed far apart. Post-abdomen large, broad, truncate, posterior end emarginate and bear- ing the
. Fresh-water biology. Freshwater biology. 698 FRESH-WATER BIOLOGY 39 (25) Cervical sinus present. No crest 40 40 (45) Valves transversely striated. Post-abdomen broad, with indenta- tion in which anus opens. Simocephalus Schoedler 1858 . 41 Body large and heavy; shell thick. Head and rostrum small. Valves large, somewhat quadrate, with rounded angles and sometimes a posterior spine; marked with oblique striae, anastomosing irregularly and with cross-connections. Two abdominal processes developed, placed far apart. Post-abdomen large, broad, truncate, posterior end emarginate and bear- ing the anal spines. Claws rather straight, always denticulate, sometimes pectinate. Summer eggs numerous; epiiippium large, triangular, with one egg. Anteimules of $ like 9 but with 2 lateral sense-hairs. First foot without flagellum and with small hook. Poor swimmer; swims often on its back. Color yellow to yellow brown. 41 (44) Vertex rounded, smooth. No posterior spine on valves. 42 42 (43) Ocellus elongated. Vertex rounded over. Claws denticulate. Simocephalus veiulus (O. F. Miiller) 1776. Ocellus large, elongated, rarely rhom- boidal. No spine on valves, though there may be a blunt posterior angle. Post-abdomen very broad, deeply emarginate; anal spines about ten, de- creasing from the claws; the larger bent and ciliate at the base. Claws long, slender, little curved, denticulate only. Length, 9. ; $, ca. Not very abimdant, but found every- where in weedy MM. 43 (42) Ocellus rhomboidal or round. Claws pectinate. . Fig. 1073. Simocephalus veluius, with epbippium. Vertex with obtuse or rounded angle. Simocephalus exspinosus (Koch) Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Ward, Henry Baldwin, 1865-1945; Whipple, George Chandler, 1866-1924. joint author. New York, John Wi
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
