TURRTTELLA (HAUSTATOR) INCRASSATA. 447 



acute point; ornamented spirally by more or less prominent ridges, varying in 

 number, position, and arrangement but not distinctly and equally triplicate and 

 equidistant as in the type T. triplicata; and also by exceedingly fine and thread-like 

 lines; suture slight; base of the shell angulated, flattened, with fine spiral ridges. 



Dimensions. — L. 40—05 mm. B. 12—18 mm. 



Distribution. — Not recognised living. 



Fossil : East Anglian Crag: Coralline to Icenian. Wexford (?). 



Miocene, Waenrode bed, Diestien, Casterlien, Scaldisien, Poederlien : Belgium. 

 Casterlien, Scaldisien, Poederlien: Holland. 



Remarks. — A difference of opinion has long existed as to the specific identity 

 or otherwise, and consequently as to the correct nomenclature of the shells 

 described respectively by Sowerby as Turritella incrassata, and by Brocclii as 

 Turbo Iriplicatus. It seems that Sowerby's name appeared on February 1st, 1814, 

 and Brocelii's during the same year, probably somewhat later. The specific term 

 incrassata has been, and is still generally used by Belgian, Dutch, and English 

 writers for the well-known Anglo-Belgian fossil which has not been recognised as 

 a recent form, the term triplicata being employed in France and Italy for the shell 

 still existing in southern seas and widely known as fossil in the Miocene, Pliocene, 

 and Pleistocene deposits of extra-British regions. Even if Sowerby's name be the 

 older by a few weeks, I doubt whether foreign Conchologists would now adopt it 

 in lieu of the one they have used for more than a hundred years ; but if I am right 

 in thinking the two shells may be regarded as specifically distinct, this will not 

 be necessary and the existing nomenclature may stand. We have both forms, I 

 consider, in the Crag, though T. incrassata is, the most common. The latter 

 corresponds with Sowerby's shell and is here figured as T. (Haustator) incrassata 

 (PL XLII, figs. 1 — 3 ; 5 — 7). The other more nearly agrees with that of Brocclii 

 and is given under his specific name of triplicata. (figs. 11 — 14). As to the first 

 named, Sowerby says the whorls are " flatfish with the lower part angular and three 

 smooth longitudinal threads " ; as to these he says, " two of them are much more 

 prominent than the third " ; his figure, which is rather unsatisfactory, shows the 

 ridges to be confined to the lower part of the whorls, the upper part being free 

 from such sculpture. In some of my specimens the third ridge is nearly obsolete. 



In Brocchi's figure of Turbo trvplicatus, on the contrary, and in some fossils I 

 have received from the Miocene deposits of Touraine, the base of the shell is 

 somewhat more rounded, while the three spiral ridges are equally strong, prominent 

 and equidistant. 



The typical T. incrassata is common in the Coralline, but rather less so in the 

 Red Crag. 



Of the three figures of T. incrassata given by Nyst in 1881, only one (op. cit., 

 fig. 12 c) seems to me (rather doubtfully) characteristic. 1 12 ft and 12 b are of the 

 1 Nyst calls this figure (12 c) T. incrassata, var. planispira. It is not the T. planispira of Wood. 



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