Tusk-sJielis^ Mail-shells^ and Limpets 187 



which is only smooth. Half-way between the margin 

 and apex is a chocolate mark of horseshoe shape. 

 The animal is white, with a large head and long awl- 

 shaped tentacles, with small eyes at their base. Foot 

 oval and broad. It occurs under stones, from low 

 water to a depth of 20 fathoms, but comes no farther 

 south than Northumberland and Durham. One form 

 of it found on the narrow leaves of Sea Grass {Zostera 

 "iiiarina) has the shell compressed so that it becomes 

 narrow and higher. This form is sometimes dis- 

 tinguished as A. alvea. The White Tortoiseshell 

 Limpet (A. virginea) is similar to the last, but only 

 half the size, rather glossy, pinkish, with brownish 

 and white rays, rather than white, though a pure 

 white variety occurs at Scarborough. Its ordinary 

 length is little more than a quarter of an inch, but 

 at Guernsey it exceeds half an inch. It is generally 

 common on stones just below low-water mark. In 

 Acmcea the apex of the shell is turned forwards ; in 

 Lepeta backwards. 



The Fulvous Tortoiseshell Limpet (Lejoeta fulva) 

 is rather smaller than the last ; of a yellow, bright or 

 dull orange colour, with white rays and fine radiating 

 ribs ; tliinner and semi-transparent, not glossy. The 

 Blind Limpet (Z. cceca) is white, thin, finely grooved 

 from the beak, about half an inch long. The animal 

 is whitish, with short tentacles, but no eyes. It is a 

 Scandinavian species, which has been taken occa- 

 sionally in a dead state from deep water between 

 Scotland and Shetland. 



The Curled Limpet (Propilidiitvi ancyloides) is 

 another ej^eless species similar to Lepeta, but with 

 longer tentacles, and the beak of the shell curled 



