Lamarck's Genera of Shells. 223 



ana, Laplysiana, and Limaciana. None of the animals of the 

 first family have any shell ; we proceed, therefore, to the 



2d Family. 

 Phyllidiana, (4 genera.) 

 Branchiae situated under the border of the mantle, and dis- 

 posed in a longitudinal series round the body. The individuals 

 of this family respire water only. 



Some of the Phyllidiana have no shell, either external or 

 internal ; others are wholly, or in part, covered by a shell, 

 sometimes composed of one single piece, sometimes of a range 

 of moveable and distinct pieces. 



1. Phyllidia. 

 This genus has no shell. 



2. Chitonellus *. 



Body creeping, elongated, rather narrow, resembling a cater- 

 pillar ; a multivalve shell on the middle of the back, through 

 its whole length, like a riband ; valves alternate, longitudi- 

 nal, almost connected by their extremities ; sides of the back 

 naked. Branchiae disposed like those of the Chitones ; foot 

 divided longitudinally by a deep furrow. 



The valves of the shell, whilst the animal is alive, are sepa- 

 rate ; but, when dead and contracted, several of them appear 

 to be united. The Chitonellus is nearly allied to the Chiton ; 

 but the looser disposition of the dorsal shell admits of greater 

 freedom of motion to the right or left, and suffers the animal 

 to bend its body to either side with facility, like a worm. The 

 longitudinal furrow in the foot, probably serves for crawling on 

 the stems of marine plants. 



Type. Chitonellus IcBvis f. 



Shell with smooth small valves ; margins very entire ; last 

 valve pointed posteriorly. 



New Holland. 2 Species. PI. VII. Fig. 110. 



• Little Chiton. t Smooth 



Vol. XV. Q 



