﻿RHYNCHONELLA. 



Gl 



bilid, and traces of two minute lateral plaits, the form and other characters exactly as in 

 the type var. acuminata, but the width less than an inch." 



1 cannot, however, offer an opinion concerning A. triangularis, not having been able 

 to procure a sight of the original specimen, and since the figure is drawn in such a position 

 as not to convey a sufficient idea of the real shape and character of the shell. 



I have not yet been able to find specimens of Rh. acuminata in our British 

 " Upper Devonian" strata, but it has been mentioned by Professor M'Coy as having 

 been found, although rarely, in the slate of Petherwin (?). 



Rhynchonella laticosta, Phillips (sp.). PI. XIV, figs. 1 — 3. 



Terebratula. laticosta, Phillips. Pal. Foss. of Devon, &c, p. 85, pi. xxxiv, fig. 



153, 1841. 



Sj)ec. Char. Shell transversely oval, wider than long ; dorsal valve regularly convex, 

 with about twenty-two large simple radiating ribs, which extend from the umbone to the 

 margin ; of these five or six compose a very slightly elevated, flattened fold. Ventral 

 valve rather deeper than the opposite one, with a shallow sinus. The surface of this valve 

 is ornamented with from twenty-one to twenty-three radiating ribs, which in both valves 

 are crossed by numerous lines of growth ; proportions variable ; length 15, width 18 lines. 



Obs. Although casts of this Rhynchonella are very abundant in grey impure Upper 

 Devonian limestone at Baggy Point and in some other North Devon localities, not a single 

 specimen could be found in anything like perfect condition, all the examples being more 

 or less crushed and contorted, so much so, indeed, that it was difficult to determine the 

 exact form, no specimen with the shell preserved having been discovered. Professor 

 Phillips mentions that the resemblance of this fossil with Von Buch's figure and descrip- 

 tion of Terebratula amjihitoma is very great, but that it differs in several particulars, and 

 with which last statement I entirely coincide. It appears to resemble nearer to the Car- 

 boniferous Rhynchonella Carringtoniana than with any other species with which I am 

 acquainted. Prof. Phillips' figured specimens are preserved in the Museum of the 

 Geological Survey, and were obtained from Baggy Point. 



Rhynchonella Pengelliana, Davidson. PI. XII, figs. 8, 9. 



Flattened and otherwise distorted external impressions and internal casts of a very 

 large Rhynchonella occur abundantly in an ochreous yellow friable sandy rock at Looe, in 

 Cornwall. None of the specimens were, however, perfect enough to admit of a complete 

 diagnostic description. 



The shell appears to have been, when perfect, transversely oval, or wider than long ; 



