108 CRETACEOUS LAMELLIBRANCHIA. 



Affinities. — This species was identified by W. Keeping with A. subdentata, 

 Romer, 1 from the Neocomian of Brunswick. I have submitted photographs of 

 the British fossil to Dr. A. Wollemann and he agrees with me in thinking that it 

 is quite distinct from A. subdentata. In the latter the shell is smaller, the valves are 

 much flatter and more elongate, and the umbones are more pointed and less 

 anterior in position. 



The ornamentation, when well preserved, is somewhat similar to that of A. 

 senecta (see above), but the shell is more inequilateral, more nearly quadrate in 

 outline, and the postero-dorsal part is more compressed. 



Remarks.— The ornamentation is often imperfectly preserved, and in some cases 

 it has almost entirely disappeared. The hinge has not been seen. 



Type. — The specimen figured by Keeping is in the Sedgwick Museum, Cam- 

 bridge. 



Distribution. — Lower Greensand of Upware. 



ASTAETE CLAXBIENSIS, Sp. nOV 



Description. — Shell small, thick, oval, longer than high, inflated, slightly inequi- 

 lateral. Antero-dorsal margin concave, postero-dorsal slightly convex. Anterior 

 margin well rounded. Ventral and posterior margins forming a regular curve. 

 Umbones prominent, close together, nearly median, curved greatly inwards and 

 slightly forwards. Lunule large, ovate, with sharp edges. Escutcheon lanceolate, 

 smooth, distinctly limited. 



Ornamentation consists of strong, narrow, concentric ribs, separated by broad, 

 deep furrows. Left valve with two stout cardinal teeth and a tooth at the margin 

 of the lunule. Margins of valves coarsely crenulate. 



Measurement* ■. 



(i) (2) (3) 



Length . 12 . 11 . 10 



Height . 10-5 . 10 . 9 



(1-3, 5) Claxby Ironstone, Benniwortb Haven. 

 (4) Spilsby Sandstone, Spilsby. 



Affinities. — Astarte claxbiensis shows considerable resemblance to certain species 

 found in the Jurassic rocks ; thus Astarte robusta, Lycett, 2 from the Cornbrash, seems 

 to differ only in having the valves more elongate and the umbonal parts narrower. 



1 ' Verstein. norddeutscb. Kreidegeb.' (1841), p. 71, pi. ix, fig. 9. Wollemann, ' Die Bivalven u. 

 Gasterop. d. deutscb. u. hoUand. Neocoins ' (1900), p. 98, pi. v, fig. 2. 



2 ' Suppl. Mon. Mollusca Great Ool.,' etc. (1803), p. 74, pi. xxxv, fig. 0. 



(4) 



(5) 



9 



8 mm 



8-25 . 



? „ 



