I02 



ACM^A. 



AcmcEa pelta, Esch., peV-ta, Fig. 89, is more 

 conical and pointed, and the outside of the shell has 



about twenty-five blunt, 

 radiating ribs. The out- 

 side is gray or striped, and 

 is sometimes verv^ beauti- 

 ful; the inside is mainly 

 white, though there is 

 Fig 89. generally a dark thread 



around the edge and a brown spot in the center. A 

 strange form is sometimes found in which the early 

 growth of the shell seems to have been formed on a 

 different plan from that of the ordinary specimen, 

 for it is smooth, brown, and has almost perpendicular 

 sides, like a Nacella; after this it suddenly changes 

 to the ordinary form. It is probable that this was 

 caused by a decided change in the abode of the 

 Limpet, perhaps from the sea-w^eed to the rock. 



A small, black, conical shell, supposed by Carpen- 

 ter to be an abnormal growth of the young of this 

 species, is now known as AancFa Asmi^ Midd. It is 

 usually found living on the shells of the Black Tur- 

 ban. Its length is. one-fourth of an inch, while the 

 ordinary shells of pelta are an inch long or more. 



AcmcE a persona, Esch., per-so^-na, is shown in Fig. 

 90. What a variety of names our Limpets offer to us, 

 and how significant they are ! Spec- 

 trum — the spectre, with its pale, 

 ghostly ribs ; patina — the dish or 

 pan, with its saucer-like shell; 

 Fig. 90. scabra — the rough Limpet, wnth a 



shell like a fine rasp; pelta — the shield; and now, 



for the last one, persona — the mask. 



