36 STOMATIA-GENA. 



lines parallel to the lip-margin pass over the ribs and interstices. 

 The interior of the mouth is furrowed and beautifully nacreous. 

 (Mart. & Langk.) 



Paumotus. 



Microtis compta M. & L., Donum Bismarckianum, eine Samm- 

 lung von Siidsee-Conchylieu, p. 49, 1871. 



M. HECKELIANA Crosse. PL 51, figs. 33, 34, 35. 



Shell suborbicular, haliotis-shaped, very much depressed, flat- 

 tened, very finely striate spirally, whitish, with little longitudinal 

 stripes of light brown on the base, not very obvious, and slightly 

 undulating, their edges serrate (dechiquetes) in a peculiar way, and 

 more pronounced in the central part of the stripes. Spire excessively 

 depressed, completely flat or a little concave ; suture well-marked, 

 provided with nodose folds or denticulations moderately spaced. 

 Whorls of the spire 3, flat ; last whorl large, with two spiral series 

 of undulations above, then obtusely carinated, becoming convex on 

 the base. Aperture large, oval, auriform, brilliantly nacreous with- 

 in. Columella forming a spiral visible as far as the apex of the 

 shell, white and shining. Peristome simple, basal and outer margins 

 acute ; outer margin angular and strongly receding below. 



Alt. 3j, diam. maj. 11, min. 8 mill. (Crosse.) 



Noumea, New Caledonia. 



Microtina heckeliana CROSSE, Journ. de Conch. 1871, p. 191, t. 6, 

 f.2. 



Easily distinguished from M. tuberculata by the flat spire, as well 

 as by the form and color-pattern of the last whorl, which has 

 tremulous or wavy serrate rays of light brown, instead of green as 

 in the other species. (Crosse.) 



Genus GEN A Gray, 1850. 



Gena GRAY, Synopsis of the Contents of the British Museum, 

 42d edition, 1840, p. 151 (no description given nor species men- 

 tioned) ; GRAY, in P. Z. S. 1847, p. 146 (no description, but Patella 

 lutea named as a species) ; GRAY, Guide to the Systematic Distribu- 

 tion of Mollusca in the British Museum, p. 159, 1857. Gena Gray, 

 A. ADAMS, Monogr. of Stomatellidse in Proc. Zool. Soc. 1850, p. 37 ; 

 Ann. Mag. Nat. Hist, vii, p. 223, 1851 ; and of subsequent authors. 

 Stomatella and Stomatia in part of early authors. 



