﻿GS 



BRITISH DEVONIAN BRACHIOPODA. 



straight, flat ; margin of the front and sides broad ; the toothed edges of the valves deeply 

 locked into each other ; plaits numerous, acnte." 



Having obtained a gfreat number of specimens of this small shell, and of the typical 

 Bh. primipilaris from a single bed and quarry (Lammaton) near Torquay, I was enabled 

 to trace every variation connecting the two. The characters brought forward in order to 

 establish a distinction between the typical specimens of Bh. implexa, or compta, and 

 B. primipilaris is the absence of any fold or sinus in the first-named shell ; but this feature 

 will not hold good in all specimens, since in some the tendency to the production of a 

 fold and sinus is more or less evident ; in fact, Bh. implexa appears to me to be a young 

 condition of the full-grown Bh. primipilaris. Bh. primipilaris, and its varieties Bh. 

 implexa and compta, occur plentifully in the Middle Devonian limestone of Barton, 

 Lummaton, and Hope's Nose, near Torquay ; of Dartington, near Totness ; Woolborough 

 quarry, near Newton Abbot, as well as those of Dock-yard and Mount Wise, near 

 Plymouth, all in Devonshire. It is also a common species in the Eifel, and I have picked 

 up a great number of examples of larger dimensions than any hitherto found in Great 

 Britain, at Reffrath, near Cologne. 



Rhynchonella angularis, Phillips. PI. XIV, figs. 11 — 13. 



Terebratula angularis, Phillips. Palaeozoic Fossils of Cornwall, Devon, and West 



Somerset, p. 89, pi. xxxv, fig. 162, 1841. 



Spec. Char. Shell small, pentagonal ; valves moderately convex and almost equally 

 deep ; beak small, with a minute circular foramen under its angular extremity ; surface of 

 each valve ornamented with from ten to fifteen angular ribs, of which a few are due to 

 bifurcation, while three or four in the dorsal valve compose a slightly produced, sharply 

 margined mesial fold and shallow sinus, with projecting edges in the ventral one. 



Proportions variable ; length 3, width 3^, depth 2 lines. 



Obs. Some uncertainty may exist with reference to the specific claims of the shell 

 under description, and which has been supposed by some palasontologists to be a young 

 condition or variation of Bh. primipilaris. I will not assert that such a view might not 

 prove correct, but must observe that the very few specimens of Bh. angularis I have been 

 able to examine differed in several particulars from Von Buck's species, and therefore, for 

 the present at least, have preferred to retain Phillips's denomination for the shell under 

 description. In Bh. primipilaris, and its young state or variation Bh. implexa, the ribs 

 are comparatively much more numerous and smaller ; they are, also, in each valve bent 

 suddenly downwards towards the margin, with a small longitudinal groove in the middle, 

 while nothing of the kind could be noticed in the few examples of Bh. angularis that have 

 fallen under my observation, and where the ribs are larger, of irregular width, few in 

 number, and going straight to the margin without being bent. Bhgnchonella angularis 



