60 MISS MAUD HEALEY ON [Feb. I9O4, 



distinct. Sowerby's ' type ' is a small specirneu from Cutch L ; but 

 Waagen 2 figures one 210 millimetres in diameter, and this shows 

 that the ribs do not change nearly so soon as in variocostatus, that 

 the back remains rounder, and that the ribs frequently trifurcate. 



P. variocostatus has fewer and thicker ribs than P. Martelli or 

 plicatilis, and the suspensive lobe runs back at a greater angle. 



P. chloroolithicus and P. Vaydelota are more compressed and more 

 evolute. 



Remarks. — This specimen is in the Buckland Collection, in the 

 University Museum, Oxford. ' Hawnes, Bedford,' is written in ink 

 on it, and it bears fragments of an old label on which 'Hawnes. . 

 va' . . is still legible, in the same handwriting as that found on 

 most of Buckland's labels. It corresponds exactly with Buckland's 

 detailed description 3 and with his figure, 1 although the latter is too 

 much reduced to be of great value. 



Olcostephan us Pallasianus (d'Orb.), var. nov. (PL XII, tigs. 1 & 2, 

 & text-fig. 3.) 



1845. Ammonites FaUasianns, d'Orb.. Murchison, De Verneuil, & Keyserling, 



'Geologie de la Russie d'Europe& des Montagnes d'Oural ' vol. ii, pi. xxxii, 



tigs 1-3. 

 1864. A. kimmeridieusis.K. von Seebach, 'Der Hannoversche Jura' Berlin, p. 157. 

 1873. A. biplex (Sow.), P. de Loriol et Pellat, ' Monographie paleontologique & 



geologique des Etages superieurs de la Formation jurassique des Environs 



de Boulogne-sur-Mer ' Mem. Soe. Phvs. Hist. Nat. Geneve, vol. xxiii, 



p. 269 & pi. ii, figs. la-\b. 

 1880. A. biph.v (Sow.), Damon, ' Geoloav of Wevmouth ' Suppl. 2nd ed. pi. ix, 



fig. 9. 

 1871. A. biplex (Sow.), Phillips, ' Geology of Oxford & the Valley of the Thames ' 



p. 333 & pi. xv, tig. 17. 

 1895. A. biplex (Sow.), Mem. Geol. Surv. ' Jurassic Rocks of Britain ' vol. v, 



fig. 72, p. 156. 



Description. — Only minute fragments of the actual shell are 



preserved. The cast is discoidal,; the 



j?ig t 3. Suture-line of wnor ^ s rounded and somewhat depressed ; 



Olcostephanus Pal- ^ e r ^ s snar P an ^ prominent, about 31 in 

 lasianus var nov number; all but three bifurcate as they 

 Nat size l )ass over on ^'° ^ e ^ ac ^ 5 these three re- 



main simple, and, judging from analogy 

 with other specimens, would each be pre- 

 ceded by a constriction if the shell were 

 preserved. The body-chamber occupies 

 nine-tenths of the last whorl. 

 Remarks. — I have identified this specimen with d'Orbigny's 

 figure (loc. supra cit.) with some hesitation, caused chiefly by the 

 cross-section of the whorls, which is more depressed, and by the 

 number of the ribs, d'Orbigny's figure showing only twenty-six, 

 of which six are simple. The suture-line also is slightly different. 



1 Trans. Geol. Soe. ser. 2, vol. v (1840) pi. lxi, fig. 12. 



2 'Jurassic Cephalopoda of Kutch ' vol. i (1875) pi. liv. 



3 ' Bridgewater Treatise' No. 6, vol. ii (1836) p. 62. 4 Ibid. pi. xlii, fig. 7. 



