INTRODUCTION. 



SuB-KiNGDOir III. MOLLUSCA. 



Body soft, fleshy, destitute both of any bony skeleton supporting 

 jointed limbs, and of a hard ringed skin, or external skeleton. 

 Generally elongate, walking on a single central foot or disk, and 

 furnished with one or more pairs of organs on the head and 

 sides. The nervous system consists of a number of medullary 

 masses distributed to different parts of the body ; one of the 

 masses placed over the gullet, and enveloping it like a collar. 



The body is furnished with a muscular coat, called a mantle, 

 endued with a glairy humour, and generally furnished with a 

 calcareous envelope called a shell, secreted by the mantle, 

 and protecting the body, or the more vital organs of the animal. 



There is generally a mantle on each side of the body, each fur- 

 nished with a shell ; but the shells on the two sides are often 

 very differently sized, that on one of the sides is in some only 

 rudimentary, and in others they both are wanting in the adult. 

 Some animals which have two unequal valves in the foetal, or 

 very young, state, lose them when they grow up. 



Mollia (sect. A. Exanguium) Androv. de Moll. 1618 ; not Eichw. 



MoUusca seu Mollia (genus Exanguium) Jonston, de Exang. 1650. 



Malacoderma Rondel. Exang. 



Mollusca (ordo Vermium) Linn. S.N. ed. 10. 641. 652. 1758, ed. 

 12. ; Muller, Z. Dam. Prod. 28. 1776 ; Bri^. E.M. 1789. 



Mollusca Poli, Test. Sicid. i. 25. 1791 (exclus. Cirripodes) ; Cu- 

 vier, Tab. Elem. 1798, Anat. Comp. 1800, Reg. Anim. ii. 1817, 

 ed. 2. 1830 (excl. Cirrhopoda) ; Lamck. Syst. 50. 1801, Phil. 



. Zool. i. 315. 1809 ; Schwieger, Naturg. 187. 612. 689. 1820. 



Mollusca pars (Testacea) Swainson, Malac. 4, 5. 1840. 



Mollusca and COnchifera Lamck. Hist. vi. 259. 1819. 



Molluscitae Schloth. Petref. 45» 1820. 



Therozoa Eichwald^ Zool. Special, i. 258. 1829. 



Paenulata Latr. 



Gangliata (Mollusca) Fleming, Brit. Anim. 224. 1828. 



