38 CARBONIFEROUS LAMELLIBRANCHIATA. 



Specific Characters. — Shell small, equivalve, gibbose, and triangularly ovate, 

 its anteroposterior diameter much less than the dorso-ventral diameter. The 

 anterior and posterior margins oblique and almost straight, the inferior margin 

 rounded. The hinge-line straight, of moderate length. The umbones pointed, 

 narrow, incurved and raised, gibbose, almost central. The anterior ears depressed, 

 well defined, and triangular, the margin falcate ; the posterior ear flattened and 

 depressed, of moderate size, the margin falcate. 



Interior. — Hinge appears to be without teeth. Adductor muscle-scar normal in 

 position. Surface smooth in the umbonal region, striated below. 



Exterior. — The surface of both valves is ornamented with numerous narrow, 

 somewhat irregular sharp radiating ridges, fresh ribs becoming intercalated between 

 the primary ones as they pass from the umbo to the circumference. Some few 

 irregular concentric rugas of growth. The anterior ears are crossed by numerous 

 fine radiating ribs, the posterior ears by about seven radiating ribs, the lower ones 

 being wider apart than the upper ones. 



Dimensions. — PL XIX, fig. 23, measures — 



Antero-posteriorly . . . .27 mm. 



Dorso-ventrally . . . .29 mm. 



Localities. — England: the Carboniferous Limestone of Settle and Hill Bolton, 

 Yorkshire ; Redesdale Ironstone, Northumberland. Ireland : the Carboniferous 

 Limestone of Little Island, co. Cork ; Town plots, Killala, co. Mayo. 



Observations. — L. desquamata is on the whole a broader and less gibbose shell 

 than L. alter nata, while its ribs are more regular in their passage across the shell 

 and better defined. The ears are also better defined and depressed, and more 

 regularly ribbed. 



This species was referred by M'Coy to Pterinea with another shell, which 

 evidently belongs to a different genus and species, Pterinea intermedia, because it 

 has a very elongate hinge, with a markedly elongate posterior ear. M'Coy's 

 description of L. desquamata is very good, and the peculiar characters of the shell 

 are easily recognised in it. I was unable to find the type specimen in the Griffith 

 Collection at the Royal College of Science, Dublin. 



Genus Paljiolima, nov. 



Limatulina, pars, de Koninclc, 1885. Arm. Mus. Roy. d'Hist. Nat. Belg., torn, xi, 



p. 240. 



Generic ( 'haracters. — Shell below medium size, obliquely ovate, almost equivalve, 

 moderately swollen. Umbones small, pointed, almost central ; ears small, depressed, 

 apparently not slit for the byssus. Exterior surface smooth, or with well-marked 



