766 



ZOOLOGY 



SECT. 



Pelecypoda. The afferent branchial vein runs through the axis of] 

 the branchia, giving off branches as it goes. The blood is carried 

 back to the ventricle on either side by a dilated contractile vessel, 

 the auricle or efferent branchial vein (I. aur. y r. aur.). 



The ccelome (Fig. 671) is a pouch of considerable size, divided 

 by a constriction into oral and aboral parts. The former is the 

 pericardium, or cavity in which the heart is lodged ; it gives off a 

 pair of diverticula, right and left, each lodging the corresponding 

 branchial heart, and communicates by a pair of apertures with 



per is t 



FIG. GOO. Sepia, median section through 

 the buccal mass. <j. buc. buccal ganglia ; 

 {/. stoni. stomatogastric ganglia ; guxt. sup- 

 posed gustatory organ ; jaic 1 , posterior 

 jaw ; jaw' 2 , anterior jaw ; ce. oesophagus ; 

 pa-ist. peristomial membrane ; rail, radula. 

 (After Keferstein.) 



FIG. 661. Sepia officinalis, enteric 

 canal, a. anus ; b. d. duct of one of 

 the portions of the digestive gland ; 

 b. m. buccal mass ; c. csecum ; i. ink- 

 sac ; i. d. ink-duct ; j. jaws ; 1. 1. 

 digestive gland ; ft", oesophagus ; />. 

 pancreatic appendages ; ?. rectum ; 

 s. y, salivary glands ; st. stomach. 

 (From the Cambrid'je Natural History.) 



the cavities of the nephridia or renal sacs. The aboral part of 

 the coelome forms the capsule (gonoccele) which encloses the ovary 

 or testis. 



The paired, plume-shaped ctenidium lies parallel with the 

 long axis of the body. It is attached throughout the greater part 

 of its length to the wall of the mantle-cavity by a thin muscular 

 fold, and consists of .numerous pairs of delicate lamella?, the surface 

 of which is increased by the presence of a complex system of fold- 

 ings. Internally the lamellas are not completely in contact, 



