SEARLESIA COSTIFER. 137 



1872. Trophon costifer, S. V. Wood, Mon. Crag- Moll., 1st SuppL, p. 204. 

 1911. Trophon (.•') costiferum, Sykes, Proc. Malac. Soc, vol. ix, p. 346. 



Specific GharacterH. — See Mon. Crag Moll., pt. i, p. 49. 



Dimensions. — L. 40 — 45 mm. B. 20 — 22 mm. 



Distribution. — Recent: North Atlantic, Porcupine Exped. (Sjkes). 



Fossil : Coralline Crag (rare) : Gomer, Ramsholt, Boyton. Reel 

 Crag {passim) — AValtonian (abundant) : Walton-on-Naze, Beamont, Little Oakley. 

 Newbournian ; Butleyan. Slains, Aberdeenshire, with other Red Crag fossils. 



Bemarhs. — The type form (fig. 1) of this variable species, the only one 

 figured by Wood, is a thick, strongly costated shell with a short canal. It is very 

 conmion at Oakley, and is fonnd nearly everywhere in the Red Crag, though it 

 has not been recorded from the Icenian. The variety given by Sowerby as M. 

 rnr/osus, var. |3, equally common at the locality named, has sculpture of a more 

 delicate character. The name of this species occurs, however, in the MS. list of 

 fossils from the Crag of Iceland by Morch and Poulsen in the Museum at Copen- 

 hagen already referred to, a copy of which Dr. Pjetursson was kind enough to 

 send me, but on examination I find the specimens differ considerably from the 

 typical Crag shell, although they seem allied to it. Jeffreys states that S. costifer 

 was dredged in the Atlantic by the Swedish expedition at 110 — 800 fathoms.^ 

 Mr. A. Bell informs me, however, that he saw some of the material brought up 

 which was much broken and in a semi-fossil condition, containing, among other 

 thmgs, fragments of Terehratula grandis and other Red Crag shells. 



The shell described and figured by Posselt as Siptio {Tritonofusus) costiferus 

 (Medd. om Gronl., vol. xxiii, p. 183, pi. i, fig. 6, 1899) = Neptunea {Siphonorhis) 

 undidata, Friele (Norske Nordh. Exped., Mollusca, vol. i, p. 22, pi. ii, fig. 33, 

 1882), is a very different species. 



Var. /3., J. Sowerby. Plate XIII, fig. 3. 



1818. Murex riigosus, vai*. jG, J. Sowerbj, Min. Conch., vol. ii, p. 225, tab. cxcix, figs. 1, 2. 

 1846. Fusus incisus, Grould (?), Otia Conch., p. 64. 



1849. Tritonium (Fusus) Sitchense (f), Middendorff, Mem. Acad. imp. Sci. St. Petei'sbourg (6), 

 vol. viii, p. 478. 



Varietal Characters. — Shell generally somewhat thinner than the type form of 

 8, costifer ; ornamented like the latter with irregular and wavy spiral lines closely 

 crowded together, with finer and rather less prominent longitudinal costee, which 

 are confined to the upper whorls. 



1 Quart. Journ. Greol. Soc, vol. xxvii (1871), p. 496; Mr. E. E. Sykes reports it (op. cit.) from 

 the Porcupine expedition, station 13. 



18 



