﻿134 UAMI'SIUIS 



1- 



Maryarun {i'liio) t>cr[fH> purciis Lea, Syn., 1870, p. 48. 



L.ani^sUis pcrpttrpiireiis Simtson, Syn., 19(30, p. 558. 



(Jnio troostoisis SowiCRHv, Conch. Icon., XVI, 1868, pi. i.xxix, 



%• 415- 



Very closely related to L. trabali'S, and is sometimes a little 

 difficult to determine badly eroded shells. L. perpurpurea 

 seems to lie thinner, more compressed, and less exaggerated 

 ill its peculiar characters than trabalis. 



Group of iMtnpsilis modioliformis. 



Shell elliptical, thin, quite evenly rounded before and behind, 

 somewhat inflated ; beak sculpture consisting of a few parallel 

 bars, looped in front, and generally open ; epidermis with beau- 

 tiful, rather broad, generally unbroken, sometimes slightly wavy 

 rays ; nacre brilliantly iridescent ix)steriorly ; teeth compressed. 

 The female shell is greatly expanded posteriorly, the outline 

 sometimes being almost arcuate on the middle base, and sweep- 

 ing around in a regular curve to the ligament. Animal with 

 mantle border often sixDtted, and in the female furnished with 

 fine, well-developed papillae on the post-ventral region ; branch- 

 ial opening large, with many strong papillae ; marsupium pro- 

 jecting greatly below the rest of the gills, rounded below ; ovi- 

 sacs large and distinct. 



Lami'Sii.is !vi()i)ior,ii'C)R.\Jis (Lea). 



Shell long elliptical or long obovate, thin, somewhat inflated, 

 with full, but not high, beaks, which are sculptured with num- 

 erous rather fine, doubly-looped ridges, the hinder loop some- 

 what angular below ; surface rather smooth and shining, olive 

 or yellowish-green, faintly rayed or almost rayless ; left valve 

 with two greatly compressed pseudocardinals, the anterior tri- 

 angular and much the higher, and two very delicate laterals ; 

 right valve with one pseudocardinal and sometimes a faint 

 one above it. with one lateral ; beak cavities shallow ; muscle 

 scars scarcely impressed, the anterior separate; nacre bluish- 

 white, often tinted with purple, iridescent behind. Male shell 

 long elliptical, sometimes slightly wider and bluntly pointed or 



