ANIMALS. 89 



Pboductus horridus, J. Sow. Brown, Fossil Conchology, pi. Ivi, figs. 13, 14, 1843 (?). 



— — „ De Verneuil, Bull. Soc. Geol. de France, 2°° serie, t. i, 



p. 29, 1844. 



— — ,, Desor, Min, Conch, de Sowerby, p. 352, pi. ccxi, cccxix, 



figs. 1, 2, 1845. 



— CALVUS, /. de C. Sow. Desor, op. cit., p. 577, pi. ccclx, ccclxv, figs. 3-5, 1845. 



— HORRIDUS, J. Sow. Geol. Russia, vol. i, p. 222, 1845. 



Strophomena aculeata, Schl. Schmidt, Petrefacten-Buch, p. 25, pi. iv, fig. 6 a, b, 1846. 

 Productus horridus, J. Sow. Geinitz, Grundriss, p. 521, pi. 21, fig. 17 a, b ; pi. xxii, 



fig. 8, 1846. 



— — „ Tennant, Strat. List Brit. Fossils, p. 88, 1847. 



— — „ De Koninck, Mem. Soc. Roy. Liege, t. iv, pp. 266-72, 



pi. XV, fig. 1 a, b, c, d, 1847. 



— — „ King, Catalogue, p. 8, 1848. 



— — „ Howse, T. N. F. C, vol. i, p. 256, 1848. 



— ,, Geinitz, Versteinerungen, p. 15, pi. vi, figs. 1-14, 1848. 



I)iac/nosis. — " Quadrangular, with a large furrow along' the middle, eared, thorny. 

 Ears prominent, sub-cylindrical. Beak incurved, large."^ (J. Sowerby.) 



The researches of Dr. de Koninck (whose synonymy for the last century I have 

 fully availed myself of) into the bibliographical history of this species, have shown 

 that it is the most anciently-recorded Productus known, having been first noticed by 

 Hoppe so early as 1745. 



Productus horridus is found under so many forms, that any one might, at first, be 

 tempted to divide it into a number of specific groups ; but I am fully convinced that a 

 more intimate acquaintance with all the various appearances and conditions under 

 which the species occurs, cannot but lead to the conclusion that it is not so far 

 divisible. In Plates X and XI will be found some of the principal varieties, which, it 

 requires to be remarked, are characteristic of certain localities ; thus the Whitley 

 specimens (PI. XI, fig. 1) are narrower and comparatively higher than those found at 

 Humbleton (PI. XI, fig. 4) and Derbyshire, and they possess a shallower median 

 furrow; while the Garmundsway (PI. X, figs. 29, 30, 31) and Thickley specimens are 

 intermediate in these respects ; besides, the Humbleton and Derbyshire varieties have 

 not the square form possessed by the latter. The former are also more decidedly 

 ridged in the longitudinal sense (compare fig. 23, PI. X, with fig. 3, PI. XI). Similar 

 varieties occur in Germany. I procured at Kamsdorf a specimen equally as wide 

 as any found at Humbleton ; whereas all the Glilcksbrunn specimens I have seen are 

 narrow, like those occurring at Garmundsway. There also appears to prevail a differ- 

 ence in the form of the boss or cardinal muscular fulcrum, which is trilobed, with the 

 lobes convex, in the Garmundsway examples (PI. XI, fig. 12) ; but bilobed, with the 



1 Mineral Conchology, vol. iv, p. 1 7, 1 823. It affords me much pleasure to state that ]^Tr. J. de C. Sowerby 

 has kindly lent me for illustration (vide PL XI, figs. 2, 3) two beautiful specimens of this shell, one of 

 which served as the original or type of the species. (Vide Min. Conch., vol. iv, p. 17, pi. cccxix, fig. 1.) 



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