﻿SCABR^. 



119 



assigned by Von Buch to the T. aliformis of Parkinson, fails in ail the characteristic 

 features of that species. It appears to be allied to, and perhaps is not really distinct 

 from, a large Bogota species figured by Von Buch for T. aliformis (' Description des 

 Petrifications recueillies en Amerique, par Alex, de Humboldt et par Ch. Degenhardt,' 

 1839, fig. 10). The figures of these American allies of T. aliformis are indicative 

 of an indifferent condition of preservation, which should induce us to distrust the value of 

 any theoretical conclusions founded upon such materials. It would appear also from the 

 general tenor of Von Buch's remarks in his memoir on the characteristic fossils of the 

 Cretaceous rocks ('Betrachtungen iiber die Verbreitung und die Grenzen der Kreide- 

 Bildungen,' 1S49) that he was even inclined to arrange all the lengthened forms of the 

 Seabrcs as a single species, or, in other words, to refer them all to T. aliformis ; he 

 also records his astonishment at its great and perhaps unexampled geographical range ; 

 that it occurs in the State of Alabama, in the mountain-ranges of Central America, again 

 in the mountains of Santa Fe de Bogota, South America. He even unites to T. aliformis 

 the T. ventricosa of Krauss from Algoa Bay, South Africa ; and remarks that it is found, as 

 if blown by the winds over the vast peninsula of Hindostan, in the south-west, 

 near Pondicherry. The examination which I have instituted leads me to reject alto- 

 gether a statement so general and unexampled ; the figure of T. thoracica, Morton, which 

 Von Buch referred to T. aliformis, and also the large Bogota shell, to which he gave the 

 same name, have the general figure short posteally, without attenuation. The costse are 

 also different in figure ; the areas and escutcheons are not delineated ; they cannot., there- 

 fore, bear a strict comparison with any known European species. 



T. ventricosa, Krauss (' Nova Acta Acad. C. L.-C. Nat. Cur.,' vol. xxii, part 2, p. 

 456, tab. xlix, fig. 2, 1850), is so important a fossil, from its wide distribution in South 

 Africa and its great numbers, and from its having been united by Von Buch to T. 

 aliformis, and very inadequately figured by Krauss, that I have been induced to subjoin the 

 following figures taken from a specimen in the British Museum, which possesses a 

 remarkably fine and numerous series numbered 49,990. The locality is Sunday's River, 

 District of Uitenhage, South Africa, at a place named Prince Alfred's Rest.^ 



.^M5i\ 



Three views of the valves of Trigonia ventricosa, Krauss, from South Africa. 

 1 See 'Quart. .Journ. Gaol. Soc.,' vol. xxvii, p. .'iOO, &c. 



