138 



UNIVALVES. 



II. WITHOUT A REGULAR SPIRE. 



PATELLA. — Limpet or Dish-Shell. 



Animal — a Limax: Shell univalve, subconic, shaped like 

 a bason, without a spire. 



THIS genus contains one hundred and six species. They 

 are very similar in form, which, with a few exceptions, ap- 

 proximates to that of a cone, with its apex a Httle blunted. 

 But, with regard to the colours and workings, they differ 

 exceedingly; some being perfectly' smooth, whilst others 

 are strongly granvilated and spinous ; and many are deep- 

 ly striated or covered with elevated tuberculated rays. 



Of the limpets which are very entire, and not pointed at 

 the tip or crown, those most worthy of notice are the P. 

 afra, P. areolata, P. flammea, P. Indica, and P. testudina- 

 ria; the latter is rather a rare species, and generally has 

 its interior of a silvery hue. The P. compressa is remark- 

 able for its narrow and lengthened form, which gives it the 

 appearance of having been squeezed or pinched. 



The P. umbellata is one of the rarities of the genus; it 

 sometimes grows to a large size ; it is a flat, broad, expand- 

 ing shell, of a blueish white colour, ha\ang its interior of 

 a glossy yellowish or brownish cast, and the tip generally 



