312 



General Biology 



mouth surrounded by chitinous teeth and the anal opening in the pos- 

 terior region. They live in mud and sand. The head-end usually pro- 

 jects above the surface of the mud in which they lie. 



Fig. 200. 



Magellania fiavescens (of the group 

 Brachiopoda). A, dorsal aspect of shell. B, 

 shell as seen from the left side, b, beak; d.v., 

 dorsal valve; /, foramen; v. v., ventral valve. 

 (From Weysse, after Davidson.) 



Anatomy of a Brachiopod, Waldheimia 

 australis. 1, mouth; 2, lophophore; 3, stom- 

 ach; 4, liver tubes; 5, median ridge on shell; 

 6, heart; 7, intestine; 8, muscle from dorsal 

 valve of shell to stalk; 9, opening of nephrid- 

 ium; 10, stalk; 11, body-wall; 12, tentacles; 

 13. coil of lip; 14, terminal tentacles. (From 

 Shipley and MacBride.) 



Fig. 201. 



A. Echiurus pallassi (of the group 

 Gephyrea). a, mouth at the end of the grooved 

 proboscis; b, ventral hooks; c, anus. (From 

 the Cambridge Natural History.) 



B. Sipunculus nudus (of the group 

 Gephyrea) laid open from the side. A, anus; 

 BD, brown tubes (nephridia) ; D, intestine; 

 G, brain; Te, tentacles; VG, ventral nerve- 

 cord. (From Sedgwick, after Keferstein.) 



C. Priapulus candatus (of the group 

 Gephyrea). a, mouth surrounded by spines. 

 (From the Cambridge Natural History.) 



References : 



Ward and Whipple, "Fresh Water Biology." 



Hegner's "College Zoology." 



Pratt's "Manual of the Common Invertebrate Animals." 



Braun & Liihe, "A Handbook of Practical Parasitology." 



W. H. MacCallunn, "A Text-book of Pathology." 



Damaso Rivas, "Human Parasitology." 



Kolle & Wassermann, "Hand-buch der Pathologenen Mikroorganis- 

 men." 



Hegner & Coit, "Diagnosis of Protozoa and Worms Parasitic in 

 Man." 



Needham and Lloyd, "The Life of Inland Waters." 



James G. Needham, "A Guide to the Study of Fresh-Water 

 Biology." 



