n CRETACEOUS LAMELLIBRANCHIA. 



ribs slender, faintly marked, sometimes indistinct in part, better marked near the 

 umbones and on the postero-dorsal region than elsewhere. Anterior teeth (about 

 five) short and nearly perpendicular; posterior (about six) more oblique, the 

 external being nearly horizontal. Margins entire. 

 Measurements : 



(i) (2) (3) 



Length 5*5 4*25 . . 3'75 mm. 



Height . 6-0 . . 4'5 . . 4'0 „ 



Affinities. — This appears to be similar to the form described as Pectunculus 

 insculptus, Reuss, from the Priesen Beds of Bohemia, but since the figures l of 

 that form show casts only it is difficult to determine its affinities. The hinge-line 

 in P. insculptus seems to be much more curved, forming a fairly sharp angle at 

 the umbo, and the teeth are also more numerous than in L. albiensis. 



In P. reticulatus, Reuss, 2 the radial ribs are much better marked than in 

 L. albiensis. 



Types. — In the Museum of Practical Geology. 



Distribution. — Lower Gault (zones ii, iii, and vii) of Folkestone. 



Limopsis, sp. Plate XV, figs. ba — c, 6 a — c. 



1897. Limopsis, sp., H. Woods. Quart. Journ. Geo]. Soc, vol. liii, p. 379, pi. 



xxvii, figs. 7, 8. 



Description. — Shell small, oval, convex, a little oblique, higher than long- 

 margins of valves not crenulate. Casts show fine radial strias, sometimes crossed 

 by a few shallow concentric furrows. 

 Measurements : 



Length ....... 8 mm. 



Height 7 „ 



Remarks. — 'At present this species is known only from internal casts, so that 

 a complete description cannot be given; it seems, however, to be distinct from 

 other forms. 3 I have not been able to make out satisfactorily the hinge 



1 Greinitz, 'Char, der Schicht. u. Petref. d. sache.-bohin. Kreidegeb.,' pt. iii (1842), p. 78, pi. xx, 

 fig. 17; TCeiiss, 'Die Verstein. der bokm. Kreidef.,' pt. ii (1846), p. 8, pi. xxxv, fig. 5; Fritscb, 'Stud. 

 im gebiete der bohm. Kreidef'.,' v. Prieseuer Schichten (1893), p. 93, fig. 1013. 



2 lieu^ss, ibid., p. S, pi. xxxv, figs. 7, 8. 



3 Compare with the following, most of which are known as casts only : 



(i) L. calvus, Sowerby, 'Trans. Geol. Soc.,' ser. 2, vol. iii (1832), p. 417, pi. xxxviii, fig. 2; 

 Zittcl, "Die Bivalv. der Gosaugeb.," ' Denkscbr. d. k. Ak. d. AVissensch. Wien. Math.-nat. CI.,' vol. 

 xxiv (18G5), p. 1(55, pi. ix, fig. 8. 



(ii) L. rhomboidulis, Alth, ' Haidinger's Naturwiss. Abhandl.,' vol. iii, pt. 2 (1850), p. 233, 

 pi. xii, fig. 17 ; l'a\rc ' Moll. Toss. Craie de Lemberg ' (lhG9), p. 121, pi. xii, figs. 11, 12. 



