424 PATELLlDiE. 



dusky. The very long tongue is armed with numerous 

 transverse series of denticles ; of these, four nearly similar 

 narrow ones, with brown hooked even extremities, form 

 the centre of the rachis, and two brown hooked lower- 

 placed broader ones flank them, bounded by three colour- 

 less accessorials on each side. The length of the tongue 

 exceeds that of the shell ; in a limpet two inches and a 

 half long it exceeded those dimensions by three-twelfths. 

 On this tongue we counted one hundred and sixty trans- 

 verse bands of teeth : as each band is composed of twelve 

 denticles, there were no fewer than one thousand nine 

 hundred and twenty teeth in all : twenty-two of the trans- 

 verse bands belonged to the winged part of the tongue. 

 The foot is either entirely of a smoky hue, or tinged with 

 dusky yellow on the disk, and bluish on the base. The 

 branchiae form a nearly complete cordon of closely packed 

 drab or yellowish plates, rounded at their margins ; the 

 series commences as if protruded from the cervical cavity 

 on the left side of the head, and coiled backwards round 

 the body to terminate, after gradually becoming smaller and 

 smaller to its origin. The mantle is yellowish white, often 

 tinged with dusky, and is fringed with fine filiform cirrhi, 

 which, as Mr. Clark was first to observe, differ in their 

 arrangement from those of the next species insomuch as 

 they are arranged in three alternations of different lengths. 

 The common Limpet is universally distributed around 

 our coasts, living on the surface of rocks and stones 

 between tide-marks. Although capable of moving about 

 with facility, when well-grown it appears to become lazy 

 and sedentary, often living in crevices, where having once 

 lodged it remains till it grows too large to come out. In 

 such cases it certainly cannot subsist on fuci, as generally 

 supposed, but must depend upon the waves for a supply of 



