44 



CHAPTER V. 



OF THE LEPAS. GENUS II. 



LEP A a 



"Animal a Triton. Shell with many valves ; the valves unequal, fixed by 



the base." — Linn. 



These shells are of various forms, but most of them are a sort 

 of truncated cone ; all the different species contain animals 

 similar to each other, but very difterent from those which in_ 

 habit any of the other shells. These shells are fixed by the 

 base to some other substance, either to rocks, stones, pieces of 

 wood floating in the sea, or to other shells, &c. They are fi'e- 

 quently found attached to the bottoms of ships in such num- 

 bers as to impede their progress in sailing. 



Most of the species consist of twelve pieces or valves, six of 

 which are called outer valves; these are nearly triangular, 

 with the pointed end upwards (/)/. 1. /. 5. a a a) ; the six 

 intermediate ones, with the points downwards (/>/. 1./. 5. hb'), 

 are termed the inner valves. They have also an operculum 

 or little door Qpl. 1. /. 5. c) composed of four valves or pieces 

 (/)/. 1. /. 3), which the animals open at pleasure when they 

 extend their tentacula for catching their prey. 



There are a few species which are found attached to whales 

 and tortoises, that are broader and flatter than the others ; in 

 these the shell appears very large in comparison with the aper- 



