MANUAL OF THE MOLLUSCA. 



Shell mimite and roundish, oval ; beaks straight ; cartilage 

 long, placed at the shorter end of the shell, contrary to that in 

 Kellia ; left valve with a minnte th.om-like cardinal tooth ; and 

 in each valve two remarkably strong lateral teeth.. 



The genus is intermediate between Montacuta and Kellia. 



Distribution. ' ' The Lasaeod usually inhabit the littoral zone, 

 where they congregate in vast numbers at the roots of small 

 sea-weeds, in the crevices of rocks, and in empty shells. L. 

 rubra, a British species, is viviparous, and lives as much out of 

 the sea as in it. Other species occur in various parts of the 

 world." — Jeffreys. 



EAMTLY Xn. — (jY<JLMiTDM.* 



In addition to the genera enumerated in W. M. ii., p. 461 

 et seq.y the following belong here : — 

 Galatea (see p. 486), and — 



FiscHERiA, Bernardi, 1860. 



Dedicated to M. Eischer, one of the editors of the Journal 

 de Conchyliologie. 



Type, F. Delesserti, Bern., inhabiting the rivers of the 

 Gaboon, W. Africa. 



Shell differs from that of Galatea in the rudimentary condi- 

 tion of the lateral cardinal teeth of the right valve, and by the 

 elongated lateral teeth being compressed, as in Cyrena ; and 

 from Cyrena by its fewer cardinal teeth, depth of the pallial 

 sinus, and by the absence of lateral teeth in the right valve. 



Family XIII. — OYPErNTD^.f 

 Cypeicaedella, Hall, 1857. 



Shell ovate, subelliptical, or subquadrate ; concentrically 

 striated ; hinge of right valve with two cardinal teeth ; the an- 

 terior tooth beneath the beaks ; posterior tooth turned obliquely 

 backwards, leaving a triangular pit, which is probably occupied 

 by a tooth in the other valve. Anterior cardinal margin with a 

 long narrow groove, apparently for the reception of a slender 

 projection of the other valve ; posterior side beveled from 

 above, edge thin ; ligament external, in a deep cavity ; mus- 

 cular scars distract, shallow ; pallial line simple. 



Fossil, 4 species. Carboniferous. Indiana. 



* See p. 461. t See p. 463. 



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