30 BRITISH CRETACEOUS BRACHIOPODA. 



Terebratula STHiATULA, Rcemer. Die Vers. Nord. Kreid., p. 39, 1840. 



— Faujasii, Reenter, lb., p. 40, tit,, vii, fig. 8, 1840. 



— auricula ta, Rcemer. lb., p. 39, tab. vii, fig. 9, 1840. 



— chrysalis, Rcemer. lb., p. 40, 1840. 



— striatula, Geinitz. Char. Petref. Kreid., pi. xvi, fig. 12, 1840. 



— chrysalis, Bronn. Leth. Geog., p. 651, pi. xxx, fig. 6, 1837. 



— striatula, Morris. Catalogue, 1843. 



— — D'Orb. Russia and Oural, vol. ii, p. 493, pi. xliii, figs. 



18—20, 1845. 



— — Reuss. Die Vers, der Bohemischen Kreideformation, p. 49, 



pi. xxvi, fig. 2, 1836. 



— chrysalis, Reuss. lb., p. 49, pi. 26, fig. 3. 



— Faujasit, Reuss. lb. p. 50, pi. xxvi, fig. 4. 



Terebratulina striata, D'Orb. Pal. Franc. Ter. Cretacees, vol. iv, p. 65, pi. 504, 



figs. 9—17, 1847. • 



Terebratula Dkfrancii, Bronn. Index. Pal., p. 1234, 1848. 



— chrysalis, Bronn. lb., p. 1232. 



— — Dav. Lond. Geol. Journal, pi. xviii, figs. 18, 20, 1847. 



— striatula, Dixon. The Geol. and Fossils of the Ter. and Cret. Form. 



of Sussex, pi. xxvii, fig. 21, 1850. 

 Terebratulina striata, D'Orb. Prodrome, vol. ii, p. 358, 1850. 



Diagnosis. Shell variable in shape according to age ; irregularly oval or pentangular, 

 tapering at the beak, longer than wide ; valves slightly and almost equally convex, some- 

 times presenting a slight longitudinal depression on each valve, beginning at about half the 

 length of the shell, and extending to the front, which is at times more or less indented, or 

 forms a regular outward curve, no traces of indentation being visible ; beak short, obliquely 

 truncated by a moderately sized foramen, formed partly out of the substance of the beak, 

 and by two small deltideal plates on either side ; the anterior portion being in general 

 completed by the umbo. Beak ridges indistinct, sloping rapidly off, giving the beak a 

 tapering appearance ; auricles on either side of the umbo very large and straight in the 

 young shells, small and oblique in the adult, and sometimes disappearing almost from the 

 convexity of this portion of the valve. Surface ornamented by a variable number of 

 radiated, small, elevated striae; few in number, and granulated in the young; very 

 numerous and smooth in the adult, augmenting rapidly at a short distance from the umbo 

 and beak by bifurcation, but more generally by intercallation. Concentric lines of growth 

 more* or less marked ; internal calcareous supports short and anneliform ; structure 

 punctuated; dimensions variable; our British specimens do not seem to exceed length 11, 

 width 8, depth 4^ lines. 



(Jbs. Many species have been made out of different ages of this variable shell, as may 

 be perceived by a glance at the list of synonyms ; having compared and studied a 

 multitude of specimens of all ages of this form, from the size of a quarter of a line to near 

 one inch in length, I feel satisfied that all those hitherto found in England belong to, and 

 are mere variations of, one single type, scarcely distinguishable from the recent Ter. caput- 



