LIMA. 79 



but semitransparent, glossy : sculpture, 25-30 raised concentric 

 plates or laminae, which are imbricate and partly overlap one 

 another in succession, the distance between them increasing 

 in proportion to the period of formation, so that the earliest 

 ones lie close together; these plates are crossed by about 

 the same number of slight ribs, which give the surface an 

 imperfectly cancellated appearance : colour white : margins 

 rounded, except at the hinge : beaks small, straight and 

 blunt, projecting beyond the dorsal margin: ears very small 

 and indistinct : cartilage small, placed in a shallow tri- 

 angular pit, which is perpendicular instead of horizontal as 

 in the last genus : hinge-line short and straight : hinge-plate 

 narrow, bluntly but distinctly crenulated across : inside pearly, 

 grooved by the reflection of the ribs and strongly crenate or 

 notched within the front margin : muscular scars slight. 

 L. 0-125. B. 0-1. 



Habitat : Shetland, in 85 fathoms, with Limopsis aurita 

 and other rare mollusks. This remote cluster of our sea- 

 girt isles, which with their craggy fastnesses guard 



" The unadorned bosom of the deep," 



has yielded more novelties of the highest interest to 

 marine zoologists than any other part of the British 

 coasts. My friend Mr. Waller detected two fresh valves 

 in some gravelly sand which I dredged in 1862 and sent 

 to him for examination ; and I found another specimen 

 this year on the same ground. The species was first 

 discovered by Professor Sars at Bergen, and described 

 by Professor Loven. Danielssen found it at Vadso, in 

 40-80 fathoms, and Lilljeborg at Christiansund. It is 

 rare. 



In consequence of the hinge-plate in certain fossil 

 species of Lima being partly toothed or crenulated, the 

 late Professor Bronn proposed in 1831 to make of them 

 a new genus, which he called Limea ; and in the fol- 

 lowing year Miinster described the same genus under 

 the name of Limoarca. Bronn remarks that, but for 

 its having only one muscular impression, this genus 



