INTRODUCTION. 
Sub-Kingdom 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. 
Mollusca 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 ; Brug. E.M. 1789. 
Mollusca Poli , Test. Sicul.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. 
Molluscitse Schloth. Petref. 45. 1820. 
Therozoa Eichwald, Zool. Special, i. 258. 1829. 
Paenulata Latr. 
Gangliata (Mollusca) Fleming , Brit. Anim . 224. 1828. 
