202 CRETACEOUS LAMELLIBRANCHIA. 



1901-2. Vola Mobeisi, P. Choffat. Faune Cret. du Portugal, vol. i, ser. 4, 



p. 147, pi. iii, figs. 5, 6. 



Non 1883. Pecten (Neithea) Morkisi, W. Keeping. Foss., etc., Neoc. Upware and 



Brickbill, 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. (X) 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 interspaces rather 

 more unequal in size, and lastly in having the areas, 1 as a rule, without ribs. The 

 concentric ornamentation agrees with that of P. (N.) quinquecostatus. 



Measurements : 



(1) (2) (3) (4) (5) (6) (7) 



Length .28 . 27 . 19 . 15 . 17 . 23 . 19 mm. 

 Height . 34-5 . 34 . 23 . 19 . 19-5 . 28 . 25 „ 



(1—4) Perua-bed, Atherfield. 

 (5, 6) Hythe Beds, Lympiie. 

 (7) Crackers, Atherfield. 

 Distribution. — Perna-hed and Crackers of Atherfield. Hythe Beds of Lympne. 



Pecten (Neithea) quinquecostatus, Sowerby, 1814. Plate XXXIX, figs. 14 — 17; 



Plate XL, figs. 1—5. 



1814. Pecten quinquecostata, J. Sowerby. Mill. Conch., vol. i, p. 122, pi. lvi, 



figs. 4—8. 

 1819. — versicostatus, Lamarck. Auini. sails Vert., vol. vi. p. 181. 



1822. — quincjuecostatus, A. Brongniart. Descript. gcol. envir. de Paris. 



In Cuvier'8 Ossein. Foss., ed. 

 2, vol. ii, pp. 251, 320, 332, 

 600, pi. iv, fig. 1. 

 quinquecostata, G. Mautell. Foss. S. Downs, pp. 128, 201, pi. 

 xxvi, figs. 14, 19, 20. 



1824. Neithea veksicostata, C. Drouet. Mcni. Soc. Linn, de Paris, vol. iii, 



p. 187, pi. vii, fig. 4. 



1825. Pecten versicostatus, Bej'rance. Diet. Sci. nat., vol. xxxviii, p. 254. 

 L827. — quinquecostatus, S. Nilssoii. lVtrit. Suecana, p 19, pi. ix, 



fig. 8 ; pi. x, fig. 7. 



1 This term in lliis sub-genus refers 1<> (lie parts of the right valve between the outermost main 

 ribs and the antero- and postero-dorsal margins. 



