﻿RHYNCHONELLA. 



65 



extends to the front. Ventral valve moderately convex, with a wide deep sinus; beak 

 acute, incurved, and showing under its angular extremity a small circular foramen sur- 

 rounded by a deltidium. The surface of each valve is covered with numerous fine stride, 

 which bifurcate at various distances from the beak and umbone, and particularly so 

 towards the margins, where from fifty to sixty may be counted. Proportions variable : 

 two specimens measured — 



Length 9, width 12^, depth 4 lines. 



7 ft 31 



>> • > )> u }> u 2 



Obs. This species is well characterised, and occurs in the Middle Devonian limestone 

 of Hope's Nose, near Torquay ; Phillips's original example is preserved in the Museum of 

 the Geological Survey. 



Rhynchonella cuboides, Sowerby. PI. XIII, fig. 17 — 21. 



Atkypa cuboides, Sow. Trans. Geol. Soc, 2nd ser., vol. v, pi. lvi, fig. 24. 



— crenulata, Sow. Ibid., fig. 17. 



— imfleta, Sow. Ibid., pi. lvii, fig. 2. 



Terebratula cuboides, Be Eon. Aniniaux Fossiles de Belgique, p. 285, tab. xix, 



fig. 3. 



Atrypa — Phillips. Palaeozoic Fossils of Devon, &c, p. 84, pi. xxxiv, 



fig. 150, 1841. 



Terebratula — A. Roemer. Dei Versteinerungen des Harzgebirges, vol. v, 



fig. 2. 



— — Bronn. Index Palseontologicus, p. 1233, 1848. 



Hemithyris — M'Coy. British Palaeozoic Fossils, p. 381, 1852. 

 Terebratula — F. Roemer. Rheinisch. Uebergangsgeb., p. 65, 1844. 



— — J. Steinenger. Geog. Beschreibung der Eifel, p. 60, 1853. 



Sp. Char. Subglobose, subcuboidal, wider than long ; dorsal valve longitudinally very 

 convex, but sloping rapidly on either side; mesial fold wide, more or less elevated. Ven- 

 tral valve much less deep or convex than the opposite one ; lateral margins slightly 

 sigmoid, front margin much elevated, forming a wide shallow square or parallel-sided 

 sinus ; beak small, and so much incurved that the foraminal aperture is usually concealed : 

 surface of both valves covered with numerous small radiating striae or small ribs, which 

 are split or grooved near the margin. Proportions very variable : two specimens 

 measured — 



Length 11, width 12|, depth 10 lines. 

 ,, 10, „ 11, ,, 5 

 Obs. I quite coincide in the view taken by Professor Bronn, that A. crenulata, 

 Sowerby, is nothing more than a synonym or variation in shape and age of B/i. cu- 

 boides, and am also imbued with the idea that A. impleta of the same author is also 



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