NUCULA. iv 
? Non 1852. Nucuta pectinara, R. Kner. Denkschr. d. k. Akad. Wissensch. Math.- 
nat. C]., vol. iii, p. 312. 
— 1885. — _~ F. Notling. Die Fauna der baltisch. Cenomange- 
schiebe (Paleont. Abhandl., vol. ii, 
pt. 4), p. 27, pl. iv, fig. 12. 
— 1889. -— — A. Fritsch. Stud. im Geb. der béhm. Kreideformat. 
ili. Die Teplitzer Schichten, p. 78. 
— 1893. — — — Ibid. y. Priesener Schichten, p. 91. 
— 1897. — — A. Hennig. Revis. af Lamellibr. i Nilsson’s ‘ Petrif. 
Suecana,’ p. 58, pl. ii, fig. 30. 
Deseription.—Shell thick, triangular or somewhat rhomboidal ; convex, slightly 
compressed anteriorly ; antero-dorsal border long, slightly convex; postero-dorsal 
much shorter and concave; ventral margin curved, the are of the curve often 
increasing towards the anterior extremity. Posterior extremity angular; anterior 
rounded or slightly angular. Umbones prominent, curved inwards and posteriorly ; 
usually placed rather near the posterior end of the shell. Lunule deeply depressed, 
broad, cordate, flattened, smooth except for growth-lines ; escutcheon long, nearly 
smooth except for growth-lines. Surface ornamented with numerous (usually 
50 to 52) radiating and rounded ribs, separated by narrower grooves; the 
grooves, and sometimes also the ribs (especially on the earlier portion of the 
shell), are crossed by numerous growth-lines. ‘There are often also a few distant 
concentric depressions. A small rib is placed in the grooves of some of the larger 
specimens. ‘Teeth: anterior about 22, posterior about 9. Adductor impressions 
deep, near the margins; the anterior a little larger than the posterior. Margins 
of valves rather coarsely crenulated. 
Measurements : 
(1) (2) (3) (4) (5) 
Length . . ; : . 29 3 20 in. F203" 2 20s es ee caumea 
Postero-dorsal margin. Bn ADO eo lot ee PR trae (2) 
Antero-dorsal margin. aye =~ 20% 9 tL A li ees 
Height . : ; : . 18 OAGE so, AU Oe ss- eel Sr teng Vie, 
Thickness. : : co § Soe ib el iS eae 
Affinities. —This species is distinguished from N, tenera, Miller,’ and N, pul- 
villus, Miiller,” of the Aachen Greensand by its coarser ornamentation, its greater 
length, broader lunule, &. From N. arduennensis, d’Orbigny, it is said to differ 
in the deep lunule and the strong ribs. 
Remarks.—The specimens from the Plinerkalk of Hundorf, &c., and the 
Plinermergel of Luschitz, &c., which are referred to this species by Reuss, are 
relatively shorter, and the umbones more acute; the examples figured by that 
1 J. Miiller, ‘Mon. der Petrefact. der Aachen Kreidef.,’ pt. i (1847), p. 17, pl. ii, fig. 1. E. 
Holzapfel, “ Moll. der Aachen Kreide” (‘ Paleontographica,’ xxxv, 1889), p. 200, pl. xxi, figs. 9—12. 
2 Miller, ibid., Supplement (1859), p. 11, pl. vii, fig. 11. Holzapfel, ibid., p. 201, pl. xxi, figs. 7, 8. 
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