PATELLA. 



Plate I. 



Genus PATELLA, Linnaus. 



Testa ovala, plus minus convexa, paMlaformi, non spiralis, 

 apice interdum cetdrali, pk'rumque plus minus antlce 

 inclinato, Sfepissime radiatim. costata vd lirata, inter- 

 dum squamata, margine plerumqiie cretmlata ; im- 

 pressio muscularis elliptica, antice interrupta. 

 Shell ovate or rounded, more or less convex, dish-shaped, 

 not spii'al, apex sometimes central, generally more or 

 less inclined anteriorly, mostly radiately ribbed or 

 ridged, sometimes scaly, generally crenulated at the 

 margin ; muscular impression elliptical, interrupted 

 anteriorly. 

 The Limpets, properly so called, have been collected 

 together under the generic title of Patella, from the re- 

 semblance of their shell to the form of a dish of that name, 

 formerly used by the Latins for carrying meat in their sa- 

 crifices. In structure it is the most simple of all shells, 

 being an unconvoluted shield, covering the soft parts of 

 the animal, more or less raised in convexity, not spiral, 

 inclining to an apex, rarely more than superficially de- 

 veloped, but sometimes bent over anteriorly into a minute 

 hoDk. From this apex radiate strias, ridges, or ribs, which 

 are sometimes scaled, and have the interstices sometimes 

 wrought into lattice work by concentric ridges. It is only 

 very rarely, however, that the shell is so sculptured, the 

 ribs or ridges being for the most part smooth, though 

 presenting abundant characteristic varieties of form and 

 distribution. The painting of the Patella is also exceed- 

 ingly varied ; the prevailing pattern consisting of rays, 

 modified by various causes to a degree which renders the 

 different states of a species often extremely diflScult of 

 identification. 



The Patella inhabit all latitudes, ranging from the 

 Equator to the Arctic Seas, where the P. testudinaUs has 

 been found by Sir Edward Belcher in Wellington Channel, 

 the most northern limit of animal life ; and they are every- 

 where abundant in their kind. Some of the finest species 

 are found about the Cape of Good Hope. 



Species 1. (Mus. Cuming.) 



Patella Mexican a. Pat. testa ohlongo-ovaid, antlce at- 

 tenuatd, inedio subacute convexa, versus marginem pla - 

 natd, radiatim costata, costis sitbcompressis, rudibiis, 

 irregularibus, plus minus obsoletis, liris intermed/is 

 scabrosis in testa jnniore ; luteo-nlbd, hie illic pnlli- 

 dissimeferritgineo-tirictd, iiitus pallidissitne furriigineu 

 tinctd. 



The Mexican Limpet. Shell oblong-ovate, attenuated 

 in front, rather sharply convex in the middle, flat- 

 tened towards tlie margin, radiately rilibed, ribs rather 

 compressed, rude, irregular, more or less obsolete, 

 with intermediate scabrous ridges in the young shell ; 

 yellowish-white, here and there very faintly rust- 

 tinged, and very faintly rust-tinged within. 



Broderip and Soweeby, ZooL Jonrii. vol. iv. p. 369. 



JJab. Acapulco ; Cuming. Mazatlan ; Carpenter. 



This fine species, the largest, in an eminent degree, of 

 the genus, is of a sharply convex form, flattened towards 

 the margin, distinguished exteriorly by a series of irregular 

 radiating ribs, which soon become obsolete as the shell 

 advances in growth. It is, within and without, of a uni- 

 form white, tinged with rust. 



May, 1855. 



