202 CRETACEOUS LAMELLIBRANCHIA. 
1901-2. Vora Morrist, P. Choffat. Faune Crét. du Portugal, vol. i, ser. 4, 
p. 147, pl. iii, figs. 5, 6. 
Non 1883. Prcren (Nerruea) Morris1, W. Keeping. Foss., ete., Neoc. Upware and 
Brickhill, p. 106 (= quin- 
quecostatus), 
Remarks.—The forms found in the lower part of the Lower Greensand are 
very closely related to Pecten (Neithea) quinquecostatus, but show, in general, 
certain small differences from the latter, so that it will, I think, be convenient to 
retain for them the name Morrisi, given by Pictet and Renevier. 
As a rule P. (N.) Morrisi is characterised by the relatively greater height of 
the shell (and consequently smaller apical angle), by the smaller convexity of the 
right valve, the rather stronger main ribs, with the ribs of the imterspaces rather 
more unequal in size, and lastly in having the areas,’ as a rule, without ribs. The 
concentric ornamentation agrees with that of P. CN.) quinguecostatus. 
Measurements : 
(1) (2) (3) (4) (5) (6) (7) 
Length. 28 eye, fe US ee Wa a ALYY , 28 , I snim, 
Height Biles CB GPR, «CIS) Cg CSS gC 
(1—4) Perna-bed, Atherfield. 
(5, 6) Hythe Beds, Lympne. 
(7) Crackers, Atherfield. 
Distribution —Perna-bed and Crackers of Atherfield. Hythe Beds of Lympne. 
Proven (Neiruua) Quinquecostatus, Sowerby, 1814. Plate XXXIX, figs. 14—17 ; 
Plate XL, figs. 1—5. 
1814. Pxroren quinquecostara, J. Sowerby. Min. Conch., vol. i, p. 122, pl. lvi, 
figs, 4—8. 
1819. —  versicostatus, Lamarck. Anim. sans Vert., vol. vi. p. 181. 
1822. —  gQuinqurcostatus, A. Brongniart. Déscript. géol. envir. de Paris. 
In Cuvier’s Ossem. Foss., ed. 
2, vol. ii, pp. 251, 320, 382, 
600, pl. iv, fig. 1. 
—- — guinquecostata, G. Mantell. Foss. S. Downs, pp. 128, 201, pl. 
xxvi, figs. 14, 19, 20. 
1824. Nerrrnka versicostata, C. Drowet. Mém. Soc. Linn. de Paris, vol. iii, 
p. 187, pl. vii, fig. 4. 
1825. Pxrcren versitcosratus, Defrance. Dict. Sci. nat., vol. xxxviii, p. 254. 
1827. — quinquecostarus, S. Nilsson.  Petrif. Suecana, p 19, pl. ix, 
fig. 8; pl. x, fig. 7. 
' This term in this sub-genus refers to the parts of the right valve between the outermost main 
ribs and the antero- and postero-dorsal margins. 
