EXPLANATION OF PLATES. 



Figures 1, 3, 4, and 6 of Plate xxxix., and 1 and 2 of Plate xli., are 

 diagrammatic, and are not drawn absolutely to scale ; it was desired to show 

 the arrangement of the organs rather than their exact size ; many drawings 

 of Molluscan anatomy are rendered unintelligible through an unnecessai'y 

 amount of detail in drawing the dissections as they are seen. The rest of the 

 figures are absolutely to scale. 



EXPLANATORY LETTERS. 



an. anus. 



ant. as. anterior cesophagus. 



a'p. reno-pallial orifice. 



ao. ce. aorta-cephalica. 



ao. vis. aorta-visceralis. 



aur. auricle. 



br. n. branchial nerve. 



c. hue. con. cerebro-buccal connec- 

 tive. 



ce. g. cerebral ganglion. 



col. mus. columella muscle. 



col. n. columella nerve. 



c. pi. pel. com. the fused cerebral, 

 pleural and pedal commissures 

 of the left side. 



c. pel. com. cei'ebro -pedal commissure. 



cten. ctenidium. 



dii. duct of Leiblin's gland. 



gl. ut. glandular uterine wall show- 

 ing through a break in the 

 mantle. 



gen. n. penis nerve (?). 



go. ovary. 



grv. mucous (?) groove. 



hej). hepato-pancreas. 



hep., du.' first; hep. du." second 

 "ibepato-pancreatic duet. 



int. intestine. 



I. m. n. left mantle nerve. 



I. pi. g. left pleural ganglion. 



I. V. con. left visceral connective. 



m. g. hypobranchial mucous gland. 



m. p. metapodium. 



neph. nephridium. 



nepli. gl. nephridial gland. 



ffis. cce. cesophageal cecum. 



fBS. gl. OBSophageal gland. 



op. operculigerous lobe of the foot. 



os2]]i. osphradium. 



p. penis. 



jyh. proboscis. 



pb. sac. proboscis-sac. 



pb. sh. proboscis-sheath. 



p. c. pericardium. 



2}d. g. pedal ganglia. 



pl.pd. com. pleuro-pedal commissure. 



J), mus. a strand of muscle attached 



to body wall and proboscis-sac, 

 post. a's. posterior oesophagus. 

 pr. pores leading to the nephridial 



gland. 

 r. m. n. right mantle nerve, 

 r. 2^1- fj- right pleural ganglion. 

 r. V. con. right visceral connective. 

 rect. rectum. 

 rect. si. rectal sinus. 

 s. siphon. 



sb. int. g. sub-intestinal ganglion. 

 sp. int. g. supra-intestinal ganglion. 

 stom. stomach. 

 tent. te)atacles. 

 tent. lb. tentacle lobe. 

 ur. ureter. 

 lit. uterus. 

 V. ventricle. 

 V. d. vas-deferens. 

 ve. br. efferent branchial vein. 

 ve. ca. vena-eava. 

 ve. ce. venacephalica. 

 re. ce. neph. nephridial branch of 



the vena-cophaliea. 

 ve. ce. per. pericardial branch of the 



vena-eephalica. 

 re. mx. vena-maxiina. 

 ve. per. vena? pericardiales. 



