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88' 



TERTIARY FAUNA OF FLORIDA 



suborbicular, subequilateral, with a short, pointed rostrum ; no lateral laminae 

 in either valve, the edge of the very oblique hinge-plate being produced on 

 each side in each valve, near the chondrophore, to perform the office of 

 laterals ; ligament very short, external ; the cardinals and chondrophore well- 

 developed, normal. 



The genus Blainvillia Hupe, 1854 (not Rob. Desv., 1830), has been re- 

 ferred to this vicinity by authors. It doubtless is identical with dementia 

 Gray and belongs elsewhere. Gray's name must be retained. 



Subfamily LUTRARIINjE. 



Geims LUTRARIA Lamarck, 1799. 

 Type L. oblonga Gmelin. 



-\- Lutricola Blainville, 1825 ; -|- PsaminophUa (Leach) Brown, 1827 ; -f- Ltcfaria Philippi, 

 1853 (-|- Cacop/wnia Gistel, 1848, yS't/t' Herrmannsen). 



Shell inequilateral, thin, compressed, siliquiform ; dorsal areas ill-defined ; 

 surface smooth or concentrically striated; beaks anterior, adjacent; pallial 

 sinus deep; siphonal and pedal gapes well-marked; ligament short, feeble, 

 not separated from the chondrophore by a shelly lamina; dental armature 

 concentrated ; chondrophore large, oblique ; resilium continuous and homo- 

 geneous between the valves ; left cardinal compressed, prominent, with an 



rostralis the anterior end is longer than the posterior. The latter is a Chinese species. R. indica 

 differs in form and proportions from R. Abercromliei Melvill, also a Bombay species. 



In the absence of specimens it is impossible to speak positively, but it is probable that several 

 other forms described from the China Seas and Indo-Pacific region should be grouped in this section. 

 This and the following recent form are included here in order to complete the revision of the group. 



f R. tenuis " Hinds," in Ads. Gen. liec. Moll. The shell is excessively thin, yellowish, polished, 

 with a nacreous sheen of much brilliancy, but internally pale straw color without nacre ; the beaks 

 are small and prominent, the surface regularly plicate with concentric waves, increasing in breadth 

 as they approach the margin, about forty in all, the small rostrum remaining, as well as the anterior 

 dorsal area, nearly smooth ; the cardinal teeth are well developed and prominent, the cartilage pit 

 small and nearly vertical. Alt. 10, Ion, 13, diam. 6 mm. 



This elegant little shell does not appear to have been described, though the name has been in 

 the catalogues for a long time. The specimen described here was dredged in Hong Kong harbor in 

 about eight feet of water, muddy bottom, by Stimpson, in 1S53. It has been compared with a 

 specimen, bearing the same name, in the British Museum, by Dr. P. P. Carpenter, and is No. 519 

 on the Museum Register. R. pukhella Ads. and Rve. {rostralis Desh.) has the same pseudo-nacreous 

 surface, probably due to some peculiarity of structure in the epidermis, and in its general characters 

 differs only by the presence of a trace of dorsal lamina anteriorly in the right valve, and in having 

 the hinge-margin somewhat more effectively modified into laterals. It should doubtless be comprised 

 in the same group. Our specimens were dredged at Hakodadi in six fathoms by Stimpson. 



