M. Deshayes' Monograph of Dentalium. 193 



tween the preceding ones, in which it is dorsal, and the following one in 

 which it is ventral. 



Length from 1 inch 4 lines to 1 inch 7 lines. Diameter of the base 

 I5 line. 



37. D. iNVERSUM, Desh. D. testd tereti, subarcuatd, subulatd, an- 

 gustd, hyalind, postice tenuissime striatd, rubeseente, antice IcEvigatd, 

 albidd; fissurd angustissimd, profundd, ventrali. 



Habitat ? 



Shell slender, rather strongly curved, subdiaphanous, milk-white at the ^ 

 base, insensibly becoming towards the middle pale red. From the junc- 

 tion of the colours extend towards the apex very numerous extremely fine 

 striae. Apex very acute. Cleft ventral, deep, but narrow. 



Length 1 inch 4 lines. Diameter of the base 1 line. 



in. Opening contracted ; two clefts at the posterior extremity. 



38. D. COARCTATUM, Lam. D. testd minutd^ subarcuaid, Itsvissimd, 

 tenui, in medio injiatd; aperturd coarctatd, non marginatd ; extremi- 

 tateposticd bifida. 



D. Gadus. (Montagu.) Soioerby, Gen. XV, f. 7, 8. 

 Var. a. Testd majore. 



D. minutum ? Linn., ed. Gmel., p. 3737, n. 9. 

 (Habitat in mari Anglico.) — Foss. in Gallia, apud Grignon, &c. Var- 

 a, in Italia. 



A very remarkable species. Shell small, thin, fragile, very smooth, 

 polished, perfectly free from strise ; slightly curved, rather pointed, gib- 

 bous in the middle, diminishing insensibly towards the apex, but more 

 rapidly towards the base, by which the latter is sensibly contracted. 

 Opening very oblique, thin, fragile. Apex in fine specimens exhibiting 

 two lateral clefts. 



Length 4 lines ; of the variety nearly 6 lines. 



IV. Shell thickened at the margin : without clefts at the posterior 



extremity. 



39. D. STRANGULATUM, Desh. D. testd tereti, subarcuatd, cinered, 

 interruptd, opacd, aperturd coarctatd; tubi margine antico infiexo. 



