•24 TESTACEA. 



Chiton— r/ie Boat Shell. 



The preceding are univalve shells in the strictest sense. Each con- 

 sists of a single piece when in its perfect state, nor does the structure ad- 

 mit of more. 



However different in form, all are inhabited by animals nearly of 

 the same species — a Limax. But the organic arrangements of some are 

 different. 



Though perhaps not absolutely in its place, let us here introduce, 

 for want of one more convenient, a few words relative to the Chiton, a 

 multivalve shell, whose inhabitant is not ver}' remote in its form and 

 nature from the Limacine race, although it is not identified as one of the 

 number. 



Let the reader figure to himself an inverted boat, he will have a 

 competent idea of the general appearance of this production. 



The animal bears considerable resemblance to that of the Patella, 

 and other univalves of the same description ; the two, however, are not 

 to be identified. The shell of the Chiton is composed of several transverse 

 plates, whereas those of the Patella, and other univalves of the kind, 

 consists of a single piece. 



Cabinets contain gigantic specimens from foreign climates. Those 

 of the Scotish shores are small, but some of them are sufficiently orna- 

 mental. 



In as as far as I have observed, all are almost littoral, as they com- 

 monly dwell in very shallow water. 



§ 1. Chiton fascicularis. — Plate V. Figs, lo, 14. 



As if this race of animals had been quite unworthy the attention of 

 mankind, a sentence is seldom be-stowed on its description. 



Length of the shell nine lines or more ; figure a long oval, narrower 

 and less regular than other species of the genus. Surface resembling 



