178 CRETACEOUS LAMELLIBRANCHIA. 



1854. Mactra anoulata, /. Morris. Cat. Brit. Foss., eil. 2, p. 2U9. 



18(35. — — F. J. Bidet and G. Campiche. Foss. Terr. Crut. Ste. 



Croix (Mater. Pal. 



Suisse, sor. 4), p. 120. 

 1870. — — F. StoUczka. Falseont. Imlica, Cret. Fauna S. ludia, 



vol. iii, pp. 55, 56. 



Non 1851. — — J. MiiUi'r. Petref. dcr Aaclien. Kreidef., pt. 2, p. 66 



(= M". Bosquetiana, Stoliezka). 



— lOOl. — — F. Sturm. Jaliili. <1. k. prcuss. fjeol. Landesanst. fiir. 



r.»L)U, vol. xxi, p. 84, pi. viii, fit;. 1. 



Description. — Shell small, convex, Rul)triangiilar, slightly incquilatoral, with 

 the antero- and |)ostero-dorsal parts bending raj)idly to the margins. Antero- 

 dorsal margin long. Anterior margin ronnded. Ventral margin convex, forming 

 an angle with the posterior margin, which is trnncated, oblique, and slightly convex. 

 Umbones prominent, pointed, curved inwards, with a carina which extends in a 

 gentle curve to the postero-ventral angle. Ornamentation consists of fine con- 

 centric ribs, wliifli l)i'coni(' fewer and stronger near llie antero-(loi-s;d and posfcro- 



(2) (3) (4) 



13 . 10 . 8 mm. 



10-5 . 8 . 7 „ 



(1 — 4) Blackdovm. 



Affinities. — In form and ornamentation M. nuijiilKfn resembles M. Warrrnana, 

 Meek and llayden,^ but the latter is of larger size and the umbones show a distinct 

 anterior curvature. 



A species found in the Aachen Grecnsand, now known as if. Bosquetiana, 

 Stoliezka, was identified with M. nnr/nJata by Midler, but is distinguished from 

 I he latter, as Stoliezka pointed out, by its greater length, smaller convexity, rotinded 

 posterior margin, and other characters. 



Ti/jje. — From Blackdown ; in the Bristol Museum. 



l^istrihntion. — Upper Greensand (zone of Selihvnhachia rostra t a) of Blackdown 

 and Ilaldon. Recorded by Barrois from the Upper Greensand of Tjulworth and 

 by Jidces-Brownc from the equivalent of the Blackdown Beds at Sidmouth. 



1 Meek, 'Invert. Cret. and Tort. Foss. U. Missouri ' (187(i). P- 208, pi. xxx, fig. 7. Wliiteaves, 

 ' Mesozoic Foss.' (aeol. Surv. Canada), vol. i (187;>), p. 142, pi. xvii, fig. 9, pi. xix. fig. 3. 



