ANIMALS. 87 
vol. i, p: 153, it is necessary to consider the Conch. Anomites productus, of Martin, 
as its type. 
Although this remarkable genus possesses in its external (concavo-convex) form a 
striking resemblance to certain species of Strophomena and Leptena, it is nevertheless 
easily distinguished from them by the want of teeth, and an area, and by the surface 
of its valves (the large one in general, and the small one occasionally) being 
furnished with spmes. So far as is yet known, Chonetes is the only long-established 
genus likely to be confounded with Productus, on account of its being spiniferous ; but 
in the former the spines are confined to the cardinal margin. 
Late researches have proved the Silurian existence of this genus. Prof. M‘Coy first 
described two species, Productus moniliferus and P. tenuccinctatus, in the Silurian rocks 
of Ireland;! Mr. Davidson next described a species, P. Twamleyi, discovered by 
Mr. Gray in the Dudley Limestone ;’ and at the same time M. de Verneuil published a 
full description of another species, P. (Leptena) enigma, found in the “ inferior Silurian 
Limestone of Osmundberg, in Dalecarlia.”*® The genus Productus may therefore be said 
to have commenced its existence in the earliest known organic age; and considering 
that no remains have yet been found in rocks more recent than the calcareous Marls of 
St. Kassian,* it may be said to have become extinct about the early part of the secondary 
period. Productuses do not appear to have existed to any extent until a considerable 
time after their first creation, smce the greatest number of known species belong to 
the Carboniferous system. 
PRODUCTUS HORRIDUS, J. Sowerby. Plate X, figs. 29, 30, 31; Pl. XI, figs. 1, 2, 3, 
AND Onda o4 Oa) LOL WL 2s: 
VERSTEINERTER Gryeuit, Hoppe, Kurze Beschreibung Verst. Gryph., &c., 1745. 
GESPALTENE GRYPHITEN, Knorr et Walch. Naturg. der Verst., vol. ii, p. 79, pl. B, id, 
figs. 5, 6; pl. D, figs. 1-3, 1768. 
= = Watch. Das Steinreich, vol. i, p. 160, pl. xix, fig. 2, 2d edi- 
tion, 1769. 
GRYPHITEN VON GuRA, Schroter. Journ. fiir die Leibh. des Steinr., vol. ui, p. 326, pl. i, 
Hon on lion 
GESPALTEN GRYPHITEN, ,, Lithol. Real u. Verballexik, vol. i, p. 309, 1779. 
GrratscHe Grypuiten, Walch. Der Naturforscher, vol. xiv, p. 24, 1780. 
GryPHiT Mit StacuELn, Schlotheim. Gesells. Naturf. Freunde zu Berlin, vol. iv, p. 75, 
pl. ii, fig. 1, 1810. 
l A Synopsis of the Silurian Fossils of Ireland, p. 25, 1846. 
* Bulletin de la Société Geologique de France, t.v; séance du 5 Mai, 1848. 
3 Idem. , 
* Herrn von Klipstein notices three species occurring in the St. Kassian beds. (Vide Karsten und 
Dechen, Archiv fiir Min., Geog. &., 1843, p. 352.) Dr. de Koninck only notices one species (Productus 
Leonhardt) in his ‘ Monographie du genre Productus.’ 
