ANIMALS. 109 
The foregoing diagnosis is given—not because those published by Von Buch and 
Geinitz are imperfect—but simply, in consequence of a wish to describe this remarkably 
variable and interesting species as it occurs in England. 
In the German specimens of Streptorhynchus pelargonatus, the umbone appears to be 
generally more incurved than in those found in this country, nearly all the latter I have 
seen having the umbonal point turned up, though not so much as it is in the specimen 
in Pl. X, figs. 21, 22. Concluding from the figures in the ‘ Verstemerungen,’ this 
species appears to have attained a larger size in Germany than in England; but I have 
lately procured at Tunstall Hill a fine specimen, much larger than any figured in this 
Monograph, though not quite so large as those represented by Dr. Geinitz. The 
irregularly twisted character of its beak is well displayed in the specimens represented 
by figs. 23, 27. Both valves are beautifully marked with slight dichotomous ridges, 
radiating from the umbonal point, and curving round to the hinge line in the cardino- 
lateral regions, as characteristic of De Verneuil’s group Arcuato-striate. 'The dental 
plates, represented in fig. 28 a,’ are in the form of slightly-raised, obtusely-rounded 
ridges; the socket plates (4) are rather large, and they project divergingly into the 
cavity of the shell; and the boss, which is bilobed and erect, occupies the inferior 
half of the fissure between the dental plates. The shell has a punctated structure ; as 
I have seen specimens, in the state of casts, exhibiting here and there numerous minute 
points, evidently casts of minute tubular perforations, and resembling, though on a 
smaller scale, what undoubtedly are casts of the latter in Zrzgonotreta cristata, hereafter 
to be noticed. The tubular perforations, or rather their casts, are larger in the umbonal 
region than in other places. 
Streptorhynchus pelargonatus bears a striking resemblance to a fossil described by 
Dr. Braun, in Count Miinster’s ‘ Beitrige,’ Heft iv, pl. ix, figs. 3 a, 6,c, under the name 
of Spirifer spurius: it occurs in the (?) Trias Marls of St. Kassian; and is evidently 
closely allied to, and congeneric with, the present species. 
The present species was described first by Baron Schlotheim, in the ‘ Denkschriften 
der Koniglichen Akademie der Wissenschaften zu Minchen,’ in which are several 
unmistakable figures of it. The so-called Spirifer minutus noticed in Professor Sedgwick’s 
paper, as occurring at Humbleton Hill, is, I strongly suspect, the same shell, since 
impressions of the latter, which might readily be supposed to belong to a minute 
Spirifer, occur occasionally in this locality. M. von Buch, describing the same species 
under the name of Orthis Laspii, in 1834, states that it was discovered by M. Laspe at 
110 au bord. La plus grande largeur est au dessous du milieu de lalongueur. Longueur, 100 ; largeur, 109; 
hauteur, 70; largeur du sinus, 0°78 de la largeur totale; largeur de l’area, 0°63.” (Hssai d’une Classification 
et d’une Description des Delthyris ou Spirifers et Orthis, par Léopold de Buch. ‘Translated par Henri 
le Cocq, Mém. Soc. Geol. de France, tom. iv, pp. 210-11, 1840.) 
1 The internal parts of the specimen represented in pl. x, fig. 28, appear larger than they really are, in 
consequence of being incrusted with particles of foreign matter. 
