I. CRUSTACEA: DECAPODA 



379 



,cf, a. 



FIG. 399. Diagrammatic section through Birgus Intro, showing lungs (from 

 Lang, after Semper), a,, a 4 , afferent blood-vessels; a/z, pulmonary chamber; e&, e/, el', 

 efferent blood-vessels; h, heart; k, gills; M, branchiostegite; />. pericardium. 



FIG. 400. Anatomy of Crayfish (Antaeus']. A, dorsal surface removed; B, scheme 

 of circulation; C, viscera removed, showing green gland and nervous system, a, anus; 

 aa, hepatic artery; ae, antenna; ai, antennula, also sternal artery; am, muscles of 

 stomach; ao, ophthalmic artery; ap, abdominal artery; av, ventral artery; bl, urinary 

 bladder; br, gill arteries; c, cesophageal commissures; gd, green gland; gn', brain; 

 gn 2 - 13 , ganglia of ventral chain; h, heart; hd, intestine; k, mandibular muscles; /, /', liver 

 and its duct; m, stomach; o, otocyst; oes, cesophagus; on, oj>tic nerve; pc, pericardium; 

 sgn, sympathetic nerve; t, t', unpaired and paired portions of testes; v, ventral blood 

 sinus; vd, vas deferens; i'l>r, veins from gills to heart. 



