926 PELECYPODA. [Eulamdlibranchia. 



Genus 4. LAS.-EA, Leach, 1827. 



Luscea (Leach), Brown, ill. Conch. Gr. Brit., ed. 1, 1827, pi. 20, f. 17, 18. 

 Type : Cardium rubrum, Montagu. Lasfa, Gray, 1847. Autono< ; , Leach, 

 1852. Cycladina, Cantraine, 1846. Poronia, Recluz, 1843. Anapa, 

 Gray, 1847. Kellia, Turton, 1842. 



Animal : The genus is remarkable for having gills in which the 

 inner lamina is both direct and reflected, while the outer one is 

 represented by the direct portion only. The hepatic and generative 

 glands are included within the general mass of the body. Hermaphro- 

 dite. (Pelseneer, Voy. " Belgica," 1903, 47.) 



Shell small, not gaping, ovato-rotund, inflated, inequilateral, the 

 anterior end longer ; hinge-plate large, interrupted in the middle, with 

 a great variability in the development of the teeth ; right valve with 

 a pustular cardinal, and on each side of it a pair of laminae between 

 which the single lamina of the opposite valve is received ; left valve 

 with a minute pustular cardinal and 2 laminae diverging from the 

 subumbonal region. The so-called cardinal is very often wanting, and 

 the laminae are irregular, and part of them often missing. The resilium 

 is enormous in proportion to the size of the shell, its ventral surface 

 with, in fully developed specimens, a thick chalky layer ; it is inserted 

 along the ventral margin of the hinge-plate or laminary platform. 

 Adductor-scars oval Pallia! line entire. 



Distribution. Cosmopolitan. 



The known species are nestlers, adhering by a byssus to the 

 rugosities of calcareous algae, barnacles, &c,, and the young are long 

 retained within the parent shell. 



KEY TO SPECIES. 



A. Shell with fine concentric striae only ; minute, ovato-rotund, 



beaks broadly rounded ..' .. miliaris. 



B. Shell concentrically striate, and with fine wrinkles and punctures. 



a. Hinge-margin pinkish, the anterior lateral teeth short . . scalans. 



b. Hinge- margin white, the anterior laterals long . - neozelanica. 



1. Las^ea miliaris, Philippi, 1845. Plate 53, fig. 14. 



Lascea miliaris, Phil., Wiegman's Archiv f. Naturgesch., 1845, 51. Kdliela 

 miliaris, Phil. : von Ihering, An. Museo Nac. Buenos Aires, xiv, 1907, 

 552. Bornia seminulum, Philippi. Modiolarca minutissima, Iredale, 

 T.N.Z.I., xl, 387. 



Shell minute, ovato-rotund, inflated, inequilateral, smooth, reddish- 

 brown. Beaks not much raised, rounded, straight, approximate. 

 Anterior end longer than the posterior, slightly oblique, the dorsal 

 margin horizontal, straight ; posterior end semicircular, basal margin 

 broadly convex. Sculpture consisting of exceedingly fine concentric 

 striae. Colour reddish-brown or yellowish with pink on the dorsal 

 parts. Interior of the same colour, smooth. Margins sharp and 

 smooth. Hinge-plate well developed, the right valve with a central 

 small pit and a pustular cardinal in front of it, the 2 anterior laterals 



