200 PERMIAN FOSSILS. 
striated, invested with a thin epidermis. Muscular impressions round; pallial sinus 
strongly marked. Hinge composed of cardinal teeth, two or a single bifid tooth in one 
valve, and one in the other; supplementary laminze small, and often obsolete. Liga- 
ment prominent, external.” (Forbes and Hanley.’) 
PSAMMOBIA (?) SUBPAPYRACEA, King. Plate XVI, fig. 6. 
PsaMMOBIA? SUBPAPYRACEA, King. Catalogue, p. 12, 1848. 
TELLINA DunELMENSIS, Howse. ‘Trans. T. N. F. C., vol. i, p. 243, 1848. 
Diagnosis —“ A thin, smooth, elliptical species. Length one third of its width: 
umbones slightly prominent, one third of the width of the valves from the anterior end : 
terminations rounded.” (King.’) 
The fossil under consideration, which rarely exceeds an inch in width, is pro- 
visionally placed in the present genus; as nothing certain is yet known respecting its 
dental and muscular characters. Judging from its outline,—some slight indications of 
cardinal teeth,—and, the absence of the posterior flexure, which certain Psammobude 
possess, notably Ze//na, the present genus seems to be its most appropriate receptacle. 
Psammobia (?) subpapyracea occurs very rarely in the Shell-limestone of Humbleton 
Hill. 
Class GASTEROPODA, Cuvier. 
Monotuyra, Aristotle. 
TRACHELIPODA, &c., Lamarck. 
PARACEPHALORES, Blainville. 
Les ApréryGiens, &c., Latreille. 
UniLocuLarres (partim), De Montfort. 
UNIVALVES. 
Diagnosis.—“ Body free: with an abdominal foot suitable for creeping, and in some 
cases for swimming. Head in general distinct, usually bearing one or more pairs of 
tentacles. Hyes situated nearly always on or near the tentacles.’ Respiratory organs 
branchial or pulmonary, and very variable in their position. Shel/ either external or 
1 British Mollusca, vol. i, p. 270. Feeling averse to overlooking the original diagnosis of a genus or 
species, I transcribe the following description of Psammobia by its founder: ‘Testa transversa, elliptica 
aut ovato-oblonga, planiuscula, utroque latere paulisper hians; natibus prominulis. Cardo dentibus 
duobus in valva4 sinistraé; dente unico inserto in opposita.”” (Animaux sans Vertébres, 2d ed., t. vi, 
pp. 170-1.) 
2 Catalogue, p. 12. 
3 Chitonide possesses no eyes. 
