TEREBRIROSTRA. 33 



Terebratula lyra, Beshayes. Ency. Meth., vol. iii, p. 1029, 1832. 



— — V. Buck. Uber Ter., 1834, et Mem. de la Soc. Geol. de France, 



vol. iii, Istser., p. 173, pi. xvi, fig. 17, 1838. 



— — Beshayes. Nouv. Ed. de Lamarck, vol. vii, p. 344, No. 49, 1836. 



— — Beslongchamps. Soc. Linn, de Normandie, 1837. 



— — B' Archiac. Obs. sur le Groupe Moyen de la Forme Cretacee, Mem. 



Soc. Geol. Fos., p. 295, vol. iii, 1839. 

 Tiugonosemus lyra, Brown. Illustrations of Foss. Conch, of Great Britain, pi. xlix, 



figs. 5, 13, 1838. 

 Terebratula lyra, Moms. Catalogue, 1843. 



— — Raulin. Patria la France Ancienneet Moderne, p. 3G2, fig. 100, 1844. 

 Terebrtrostra lyra, B'Orb. Pal. Franc. Ter. Cretacees, vol. iv, p. 129, pi. 519, 



figs. 11, 19, 1847, 

 Terebratula lyra, Bujardin. Die. Universelle d'Hist. Nat. Mollusques, pi. ix, 



figs. 5-6, 1848. 

 Terebratula lyra, Bronn. Index Pal., p. 1241, 1848. (But not his Synonyms, 



which are very defective.) 

 Terebrirostra lyra, B'Orb. Prodrome, vol. ii, p. 173, 1850. 



— — D'Orb. Journal de Conchyliologie, vol. ii, p. 224, 1851. 



Diagnosis. Shell inequivalve, of an elongated, irregularly oval shape, moderately 

 convex, rather compressed in the middle ; beak much produced and elongated, very often 

 exceeding in length the remaining portion of the shell, straight or gently curved, while 

 tapering gradually to its extremity, which is truncated by a rather small transversely oval 

 foramen, partly completed by a long and narrow deltideum, longitudinally depressed, and 

 extending from the extremity of the beak to the hinge-margin ; on either side a well- 

 defined, almost flat, false area is perceptible. 



Smaller valve oval or irregularly pentagonal, tapering at the umbo, widest near its 

 middle, slightly curved or straight in front ; valves ornamented by a great number of 

 diverging, irregularly-disposed rounded costse, sometimes bifurcating, more commonly 

 augmenting by numerous intercalated plaits at different distances from the beak and 

 umbo ; these are intersected by concentric lines of growth, more numerous near the 

 margins. The internal dispositions of the calcareous supports are as yet unknown ; 

 structure punctuated; dimensions variable. Length of the largest specimen 2 inches 3 lines, 

 width 10, depth 7 lines. 



Obs. This is one of the most beautiful among the Brachiopoda, and is much sought 

 after by collectors, from its elegant shape as well as its rarity-, the great length of its beak is 

 one of its most striking features ; as we have already stated, it often exceeds considerably 

 the remainder of the shell, especially in young individuals ; but, as judiciously observed by 

 M. D'Orbigny, it seldom extends with age ; on the contrary, the pallcal portion becomes 

 more elongated as well as augmented in width, so that in the generality of adult specimens 

 the body of the shell exceeds the dimensions of the beak. The form and arrangement of 

 the costa? are likewise very remarkable ; they are rarely straight, except in the young, but 



