PLATE XIX 



1. Stwmbus I'ugilis. 



2. Murcx saxatilis. 



'3. Haly oil's vulgaris, its shell taken away, seen on the hack, and the c 

 of the branchial cavity put asunder. 



A. The large muscle which attaches the animal to the shell. 



a. The anus. | c. The viscous organ. 



bb. .. branchiae. | d. .. heart in its pericardium. 



4. Halyotis, etc. the pericardium and branchial cavity opened. 



A. The large muscles above. 

 a. .. anus. 

 bb. .. branchiae. 

 c ,. viscous organ. 



5. The heart and huge vessels n 

 a. i. As the preceding figure 

 h. The right branchial veil 



A. The heart. 



e. .. right auricle. 



f. .. left auricle. 



g. . . heart surrounding the rectum. 

 ii. ,. branchial arteries. 



igni/icd. 



fissuretla entire, covered with its te 

 mantle. 



open. 



a. The disk of the foot. 

 bb. circular muscle which 

 joins it to the shell, 



eh is set in the edges of its 



and which has been 

 cut. 



k. 

 t. 



mm. 

 nn. 



auricles, 

 intestine. 



b. A portion of this muscle re- 



maining with the man- 

 tle. 



cc. The mantle thrown back, and 

 seen on the under side. 

 d. .. hole with which it is 



pierced. 

 ee. .. branchiae. 

 f. .. anus. 

 , f 'ermeius, Adanson. 



c. The tentaculal 

 y. eyes. 

 P. .. foot. 

 F. Cylindrical filaments. 

 The same animal seen underneath. 



p. The foot put on one side, to make it more apparent 

 B. The mouth. 



pharynx, 

 salivary glands, 

 lateralganglionsoftlie braii 

 extremity of the tongue, 

 liver. 



n. Operculum. 

 M. Mantle. 



A. Aperture by which the animal 

 breathes. 



