SPIRIFERA. 29 



slightly incurved, with a smooth mesial sinus extending from the extremity of the beak to 

 the front, and to which in the dorsal valve corresponds a rather wide, smooth, prominent, 

 mesial fold. Each valve is ornamented by from twenty to thirty simple, obtusely rounded 

 ribs. 



Length 15, width 15, depth 13 lines. 



Obs. No reference as to figure is given by Lamarck ; but it is stated that the fossil 

 was found at Bensberg, near Cologne. M. Valenciennes informed me, when sending his 

 type for my inspection, and which is preserved in the Museum du Jardin des Plantes in 

 Paris, that he had received the shell from which he established the species in 1817 from 

 Professor Noggerath, while on a visit to Bonn ; and it was figured by myself in the ' Annals 

 of Nat. Hist.' for 1850. A similar specimen was illustrated and described in 1822 by 

 Schlotheim, under the designation of Terebratuliies ostiolatus, and subsequently placed 

 among the Spirifers by Von Buch, and by Bronn in Konig's genus Trigonotreta. But 

 since Valenciennes appears to have been the original describer of the species, it should 

 retain the name of Icevicosta, and I am glad to find that Professors Schnur, M'Coy, 

 Morris, and several other palaeontologists, have adopted this view. To Professor Quenstedt 

 we are indebted for an excellent figure, showing the shape and position of the spiral 

 appendages. 



Sp. laevicosta does not appear to be a very common fossil in Great Britain. It occurs 

 in the Devonian shales of the Valley of the Rocks, Linton, North Devon. Phillips's figured 

 specimen, which is a mere incomplete impression of the ventral valve, is preserved in the 

 Museum of the Geological Survey. It has also been found in Middle Devonian limestone 

 near Newton Abbot. On the Continent it is common in the Eifel, at Chimay, &c. 



Spirifera speciosa, Schlotheim (sp.). PL VIII, figs. 6 — 8. 



Terebratulites speciosus, Schlotheim. Tascbenbuch fur die gesammte Mineralogie, pi. ii, 



fig. 9, 1813. 



— paradoxus, Id. lb., pi. ii, fig. 6. 



— speciosus, Id. Nachtragen zur Petrefactenkunde, pi. xvi, fig.l, 



1822. 



— intermedius, Id. lb., fig. 2. 

 Trigonotreta speciosa, Koenig. Icon. Foss. Sectiles, iii, pi. vi, fig. 71. 



— — Bronn. Letbsea Geog., pi. ii, fig. 15. 



Delthyris microptera, Gold/., in Von Dechen's Translation of Sir H. De La Beche's 



Manual, p. 525, 1833. 

 Spirifer speciosus, Von Buch. Ueber Deltbyris oder Spirifer und Ortbis, p. 35, 1837; 

 and Mem. Soc. Geol. de France, vol. iv, p. 180, pi. viii, fig. 4, 

 1840. 

 — — Phillips. Pal. Foss. of Cornwall, Devon, and West Somerset, p. 77, 



pi. lviii, fig. 134, 1841. 



