58 THE NAUTILUS. 



FAMILY XUCULIDAE. 



The Xuculida? or Xut shells are small, pearly, angular shells. 

 They commenced iu the Lower Silurian and are abundant in all the 

 various formations since. JSIost of genera belonging to this family 

 are known only as fossils. Three of the living genera, Nucula, Leda 

 and Yoldia inhabit New Eng. and two are rejireseuted iu E,. I. 



Genus Xacula, Lamarck, 1799. 



There are about fifty species, inhabiting all parts of the world, 

 most of which are found iu deep water. Five species are in Xew 

 Eug. two of which probably inhabit R. I. 



196. — Xucula clelphinodonta, ]Mighels. 



Syn. : 



Nucula corticata, HolbolL, Mbller. 



Shell small, obliquely ti-iangular, very bi'oad ; beaks nearly at the 

 posterior end, elevated and tumid ; hinge with three posterior and 

 seven anterior sharp elongated teeth ; surface with coarse lines of 

 growth ; epidermis olivaceous. Length tVo, height tVo, breadth rio 

 of an inch. 



This species was fouud in large numbers in the stomachs of Cod- 

 -fish, taken in Casco Bay, and described by Dr. ]\Iighels in Journ. 

 Bost. Soc. Nat. Hist, iv, 1842. It inhabits soft mud from ten to one 

 hundred fathoms water from Cape Cod to Greenland, and is included 

 among the shells of R. I. only on the authority of Stimpson, who says 

 it inhabits the whole coast, laminarian region, and of Prof. Verrill 

 who found it in twenty-nine fathoms, east of Block Island and off" 

 Gay Head. 



197. — Xucula proxima, Say. 



Shell small, thick and solid, very oblique, ovate-triangular; beaks 

 elevated, inclined forwards ; surface crossed by minute lines, both 

 radiating and concentric ; epidermis light olive with darker zones ; 

 interior lined with pearly nacre ; margins finely creuulated ; hinge 

 with twelve teeth before the. beaks and eighteen behind them. 

 Length 2*0, height £^, breadth 1 inch. 



