LEPAS. 63 



heel, which terminates the carinated edge of the upper 

 part of the valve. The two superior valves end in a 

 point above the dorsal valve. The shell is very thin 

 and light, of a horn colour, and in appearance resem- 

 bling pieces of dried bladder more than any other sub- 

 stance. 



Mr. Montagu, to whom we are indebted for the best 

 information relative to this species, says that the colour 

 of the shell, while containing the animal, is bluish ; that 

 these shells were once thrown up in abundance on the 

 south coast of Devon, between Milton and Shurlstone ; 

 and that they were attached in groups, some to a yellow 

 variety of the Fucus vesiculosus, others to a slender- 

 leaved Conferva; one group to the quill feather of a 

 gull, and another to a bit of charcoal. Each was 

 fixed to its respective substance by a short pedicle, 

 which shrinks so much in drying, that the shell, as 

 figured in pi. 10, appears seated on the Fucus without 

 any intermediate support. 



This must be considered as a rare species ; for if we 

 except a solitary specimen found by the late Mr. Bryer, 

 and its accidental occurrence on the coast of Devon, it 

 has not been observed for a period of more than forty 

 years. The opportunity of collecting them in Devon- 

 shire seems to have been of very short duration, since 

 Mr. Montagu remarks, that in two or three days after 

 their appearance, there was scarcely a vestige of them 

 left. 



The specimen figured in pi. 10. was covered with a 

 greenish film. 



