On Cretaceous Cephalopoda from Zuhtland. 283 



Museum, No. 50065), transitional to P. mirapelianum, d'Orbigny sp. 

 there is only one auxiliary lobe less than in the present specimen, and 

 the suture-line describes a similar curve, but the lateral lobe is slightly 

 deeper than the ventral lobe. 



Shumard's original P. acuto-carinatum* is more evolute and much 

 more distantly costate than the present species ; but the form figured 

 as " Sonneratia acuto-carinata, Typus," by Lasswitzt forms a closer 

 approach to P. multiftdum and to P. manwanense than to Shumard's 

 type or to d'Orbigny's species. The specimen figured by B6se as 

 Schloeribachia aft', acuto-carinata is similarly closely costate, but 

 differs from the Zululand species in the whorl-section, and in the very 

 pronounced forward projection of the peripheral portion of the costae. 

 A specimen of P. cf. perini'oiin, v. Buch, from Velez, Colombia, in the 

 British Museum, || shows similar peripheral projection ; but the ribs, 

 all of which are single, have the peculiar perpendicular forward edge, 

 reminiscent of such large examples of P. roissyanuw, d'Orbigny sp., 

 as that figured by Parona and Bonarelli.lf The suture-line of the 

 evolute Mexican example, on the other hand, shows great resemblance 

 to that of the large specimen here figured, except that there are two 

 more auxiliary lobes in the latter. 



One of the specimens included by White*'* in his A. buarquianus 

 seems close to the present species, but the type (White's figs. 3 and 4) 

 has distant and single costae. 



The fragments recorded by Crick, since mounted in plaster, 

 probably belong to a large specimen of this form. Splienodiscns sp., 



* In Marcy, " Explor. Red Elver Louisiana" (1853), Appendix E, 'Pal.,' 

 p. 209, pi. iii, fig. 1. The thickness of this form appears to be only about 

 20 per cent, of the diameter. 



f Loc. cit. (1904), p. 21, pi. xvii (v), fig 1 . 1, = A. peruviamis, Marcou, V, 1 a, b 

 only, non v. Buch (B.M., No. 12718, Geol. Soc. Coll.). 



J Schlagintweit (" D. Fauna d. Vracon und Cenoman in Peru," ' N. Jb. f. 

 Min., etc./ Beil. Bd. xxxiii (1912), pp. 64 and ft'., includes in " Schloenlachia " 

 roissi/ana, d'Orbigny sp., not only P. acuto-carinatiim (already united with 

 d'Orbigny's species by Lasswitz, 1904, and Douville, 1906), P. mwltifidum, 

 P. mirapelianum (as varieties), further P. buarquianum (White), P. perwoianum 

 (v. Buch), P. viirbonariiim (Gabb), P. lelknapi (Marcou) [holotype in B.M., No. 

 12663, Geol. Soc. Coll.], and other comparable forms, bvit, probably quite 

 wrongly, also Lea's A. americanus, apparently a PulckMia. 



Loc. cit. (1910), p. 65, pi. ii, figs. 1-3. 



|| No. C4266, comparable with fig. 6 of pi. i in v. Buch (' Petrif. Eecueill. en 

 Ainer. p. M. A. Humboldt et M. Ch. Degenhardt,' Berlin, 1839, p. 5), and more 

 closely costate than A. peruviamis, Marcou, V, 1, non v. Buch (B.M., No. 12664 

 Geol. Soc. Coll. and writer's coll.). 



^T Loc. cit. (1896), p. 88 (36), pi. ii, fig. 8. 



** Loc. cit. (1887), p. 222, pi. xxiv, figs. 5 and 6 only. 



