218 PLIOCENE MOLLUSCA. 



Dimensions. — L. 20 mm. B. 7 mm. 



Distribution. — Not known living. 



Fossil : Waltonian Ci^ag : Little Oakley. Newbournian : Wald- 

 riiigfield. 



Bemarhs. — One of the specimens now figured is from the Reed collection at 

 the York Museum. It is the one originally found by Mr. A. Bell, and bears his 

 undescribed name of Fleurotoimi decorata. It is alHed to 0. hijmnctula, but is 

 larger and more strongly sculptured ; among a number of specimens it can be 

 separated without diflficulty. I have obtained six or eight similar examples at 

 Oakley which appear to be the same. None of them have the smooth or polished 

 appearance usually shown by this group of shells. This form might be found 

 probably at other Crag localities if specially looked for. 



Oligotoma bipunctula (S. V. Wood). Plate XXVII, figs. 12—15 ; Plate XXVIII, 



figs. 5— S. 



1848. Pleurotoma semicolon, S. V. Wood, Mon. Crag Moll., pt. i, p. 54, pi. vi, fig. 3 h. 

 1879. Pleurotoma bipunctula, S. V. Wood, 2nd SuppL, p. 36. 



Specific Characters. — Shell small, subfusiform, turreted ; whorls l)ut slightly 

 convex, not keeled ; spire elongato-conical, ending in a blunt point ; ornamented 

 by rather strong spiral ridges, two of which near the base of the whorls are 

 connected longitudinally so as to become cancellate ; suture slight ; mouth oval, 

 narrow, angulate above, ending in a short symmetrical canal; columella sinuous; 

 outer lip regularly rounded. 



Dimensions. — L. 12 mm. B. 5 mm. 



Distribution. — Not known living. 



Fossil : Coralline Crag : Gedgrave. Waltonian : Little Oakley. 

 Newbournian : Sutton, Waldringfield ; probably elsewhere in the Red Crag. 



Scaldisien : Belgium. 



BemarJcs. — Among many specimens of the present group from Oakley, most of 

 them rather worn, I have about a dozen which, agreeing more or less nearly with 

 Wood's figure of Pleurotoma hijmnctula, separate themselves from the other Crag 

 Oligotomas by their form and sculpture. I have two separate varieties of this 

 species which at first I was disposed to regard as distinct, the one represented 

 by PI. XXVIII, figs. 5 and 6, the other by figs. 7 and 8. On the whole, I think it is 

 better to unite them under the present name. The correct determination of these 

 nearly allied and often imperfect fossils is always a matter of difficulty, and 

 sometimes of doubt. The present form and the one next to be described have 

 not been recorded except from the Pliocene deposits of the Anglo-Belgian basin. 



