Ill 



Explanation of Plates. 

 Keference Letters. 



Al.c.l. oosophagus. 



Al.c.2. stomach. 



Al.c.S. straiglit division of the 

 intestine. 



Al.c.S'. sac of crystalline style. 



Al.c.3". digestive division of the 

 straight intestine. 



Al.c.4. spiral division of the 

 intestine. 



Al.c.5. coiled division of the in- 

 testine. 



Al.c.G. rectum. 



All. anus. 



Add.a. ant. adductor muscle. 



Add. a', ant. adductor impres- 

 sion. 



Add.p. post, adductor muscle. 



Add.p'. post, adductor impres- 

 sion. 



Art.jm. anterior pallial artery. 



Art.j)p. right posterior pallial 

 artery. 



Art.i^p' . left post, pallial artery. 



Artvj). viscero-pedal artery. 



Art.v. visceral artery. 



Art.j). pedal artery. 



A. lab. right and left lahial 

 arteries. 



Ao. aorta. 



Aur. auricle. 



Ba. bull)us arteriosus. 



Br'. l)ase of right ctenidium. 



Br.E. external branchia. 



Br. I. internal branchia. 



Br.E.l. inner lamella, external 

 branchia. 



Br.E. 2. outer ,, 



Br.I.l. ,, ,, internal ,, 



Br. 1. 2. inner ,, ,, ,, 



Br.1.3. „ „ „ „ 



membranous portion. 



Br.ajf. com. afferent branchial 

 vessel. 



Br.eff. com. efferent branchial 

 vessel. 



Br.eff'. efferent branch, vessel. 



Br.aff' . afferent branch, vessel. 



Br.j.l. inter-filamentar junct. 



Br.j.2. inter-lamellar junction. 



By.ij, byssus gland. 



By', pedal groove. 



By. byssus thread. 



Com. cerebral commissure. 



Coii.cv. cerebro -visceral con- 

 nective. 



Con.cp. cerebro-pedal connec- 

 tive. 



Dg. digestive gland. 



Ep.I.l. epithelium of wall of 

 crystalline style sac. 



Ep.1.2. elongated cells in wall 

 of crystalline style sac. 



Ep.1.3. epithelium of intestinal 

 div. of straight intest. 



Ep.op. pigment cells of an eye. 



Ep.p. epidermis of the foot. 



