MENESTIK) DERIVATA. 583 



DimeiiHlons. — L. 2 mm. B. J mm. 



Distribution. — Not recorded liviiifr. 

 Fossil : St. Krth. 



Femarh.—Ur. Bell states {op. cit.) that there is a specimen of this shell fi-om 

 St. Erth in the Warburton Collection, but I have not seen it. Comi)arino- the one 

 from the British Museum now figured with that next to be described, which 

 belongs to a similar group, but is not the same, it is interesting to find these two 

 distinct forms, one from St. Erth and the other from liridlington, representing 

 deposits widely different both as to age and locality, which are yet closely allied. 



Menestho derivata (S. V. Wood). Plate L, fig. 4. 



1878. Blssoa sulcosa, Leclie, not Mighels {fide Odh.ier). K. S^eusk. Vet.-Acad. Handl., vol. xvi, p. 39. 



1879. Odosiomia derivata, S. V. Wood, Mon. Crag Moll., 2nd Soppl., p. 40 (fig.). 

 1884. Amaura sulcosa, Jeffreys in Lamplugh, Quart. Jonrn. Geol. Soc, vol. xl, p. 319. 



1915. Menestho frtmcatida, Odhnor, K. Svensk. Vet.-Akad. Handl., vol. liv, p. 175, pi. i, figs. 13-16. 



Specific Characters.— ^heW small, ovato-elongate ; whorls 4—5, compressed, 

 squarely turreted, the last much the largest, two-thirds the total length ; orna- 

 mented by fine and more or less inconspicuous spiral lines extending to the base ; 

 spire elevated, diminishing rapidly in size upwards to a rounded and truncated 

 ponit ; suture deep, somewhat channelled ; mouth ovate, equal to the spire, 

 angulate above, rounded and a trifle expanded below; umbilical chink very 

 slight. 



Dimensions. — L. 4 mm. B. 2 mm. 



Distribution. — Recent : East Greenland, Spitzbergen, Nova Zembla. 

 Fossil: Icenian Crag : Bramerton. Bridlington. 



RoiKirks. — The minute fossils here described, several S})ecimens of which were 

 found by Mr. Bell when examining Mr. Headley's Collection, are, I think, 

 the same as the one from Bramerton figured by Wood in 1879 {op. cit.) as 

 Odostomia derivata. The latter had been discovered by Mr. Jas. Reeve among a 

 quantity of small shells he had extracted from the sand of the Bramerton pit, 

 being afterwards sent for examination to the former, who considered they were not 

 genuine Crag fossils but might have been introduced from some Upper Eocene or 

 Oligocene deposit, once existing in North-Eastern Norfolk, through which a stream 

 had discharged into the Fluvio-marine (Icenian) estuary. The presence of similar 

 forms now existing near Spitzbergen and formei-ly in the glacial deposits of 

 Bridlington seems to me unfavourable to the derivative hypothesis. In 1884 

 Jeffreys referred our fossils to the Bissoa snlcosa of Leche, but that specific name 

 had been already used by Mighels (1843) for what Dr. Odhner states was a different 

 shell.^ In 1915 the latter authority proposed to call the former Menestho triin- 



^ See Fhasianella sulcosa in Gould's Inv. Mass., ed. 2, p. 297, fig. 565, 1870. 



