698 DR. GWYN JEFFREYS ON THE MOLLUSCA OF THE [Juue 7, 



Distribution. Falmouth, and St. Magnus Bay in Shetland ; single 

 valves {J. G. J.) ; Algiers (Joli/), a perfect and living specimen ! 



Fossil. Pliocene: Coralline Crag, and variety as M. cylindrica 

 {Wood) ! ; Fiume Oreto, Sicily {Brugnone) ! 



Allied to M. suhstricita ; perhaps viviparous and quasi-parasitic or 

 commensal, like that species. Mr, Wood proposed the generic name 

 Sphenalia for these and similar species. 



(^ i). MONTACUTA SUBSTRIATA, MoutagU. 



Ligula suhstnata, Mont. Test. Brit. Suppl. p. 25. 



M. substriata, B. C. ii. p. 205 : v. p. 177, pi. xxxi. f. 6. 



' Lightning ' Exp. St. 2. 



'Porcupine' Exp. 1869: St. 3, 10, 13, 14, 23fl, North Channel. 

 1870 : Mediterranean, off Rinaldo's Chair. 



Distribution. Finmark to the Mediterranean and Adriatic ; 2- 

 250 fms. 



Fossil. Pliocene and Post-tertiary : Norway, Coralline Crag, and 

 Italy. 



Inhabits the ventral spines of many kinds ot Echinidse. The fry 

 is almost globular, like that o( Kellia suborbicidaris ; and the beak is 

 placed in the middle of the dorsal area. 



There are several obsolete synonyms. 



l/ 6. MoNTACUTA BIDENTATA, MontagU. 



Mya bidentata, Mont. Test. Brit. p. 44, t. 26. f. 5. 



Montacuta bidentata, B. C. ii. p. 208, pi. v. f. 1 ; v. p. 177, 

 pi. xxxi. f. 8. 



'Porcupine' Exp. 1869: St. 2, 9, 16, 17, 18, 18b, 19, Lough 

 Swilly. 1870: Atlantic, 2, 13, 16, 17a, off Cape Sagres, 26, 30; 

 Mediterranean, Algesiras Bay, 50, 55, G. Bona, Adventure Bank. 



Distribution. Finmark and Faroe Isles to the Mediterranean, 

 Adriatic and Archipelago, and Madeira; shore-100 fms. 



Fossil. Pliocene and Post-tertiary : Norway, Sweden, Great Britain 

 and Ireland, Belgium, and Italy; 0-130 ft. 



Not M bidentata of Gould, which is M. elevata of Stimpson. Nor 

 is M truncata of S. V. Wood (as I once supposed) a variety of the 

 present species, although they are closely allied. M. elliptica, of 

 the last-named author, appears to be a variety. Among the synonyms 

 are Arcinella Icevis of Philippi and Mesodesma exiguum of Loven. In 

 some specimens the layers of growth are so strongly marked as to 

 form ridges. 



/^ 7. Montacuta ovata', Jeffreys. (Plate LXI. fig. 4.) 



Shell triangularly round, with a somewhat oblique outline, rather 

 convex, moderately solid, lustreless : sculpture none, except irregular 

 lines of growth : colour whitish : epidermis inconspicuous : margins 

 abruptly truncate at the smaller or posterior side, distinctly curved 

 in front, elevated and rounded on the anterior side : beaks small, in- 

 flected, with a deep indentation below ; they are placed close to the 



1 Oval. 



