553 mk. l. p. spath ox [Dec. 1 913, 



(2) CALLOVIAN. 



Genus Eeineckeia. Bayle, 

 Reixeckeia afF. htjxgarica Till. (PI. LII, fig. 3.) 



1911. A. Till, 'Amm, Fauna des Kellowa3" von Villany' Beitr. Palaont. Geol. 

 CEsterr.-Ung. vol. xxiv, p. 10 & pi. i (v), figs. 1-2 ; also text-tig. 11. 



There is one specimen preserved in red marble, streaked with 

 green, and slightly slickensided in places on the back. Its 

 dimensions are : — 



Diameter 60 millimetres. 



Height of the last whorl 33 per cent, of the diameter. 



Thickness of the last whorl ... '28 per cent, of the diameter. 



Umbilicus 40 per cent, of the diameter. 



These measurements agree almost exactly with the dimensions 

 given by Dr. Till, and the sculpture and section also are practically 

 identical. 



The last whorl shows about thirty-two primary costse, each 

 giving rise to two or three secondaries of equal strength and 

 strongly prorsoradiate character. The primaries are short sharp 

 ridges rising to an elongated spine at the point of furcation, and 

 only the innermost whorls bear the rounded tubercles which 

 characterize the anceps group. There are four constrictions on the 

 last; whorl, more strongly inclined forward than the costse ; and 

 since the costae also bi- and trifurcate somewhat irregularly, and 

 since some of them, especially those bordering the constrictions, 

 remain single throughout, the sculpture is altogether irregular. 



The ventral furrow is very distinct, and bordered by the strong 

 slightly-thickened ends of the secondaries, terminating abruptly at 

 the groove. 



The umbilicus is wide, with a nearly perpendicular border. 



Dr. Till points out the differences of his form from Reineckeia 

 Tciliani (Par. & Bon.), R. straussi (Weith.), R. greppini (Opp.), 

 and R. fraasi (Opp.). The ammonite under consideration also bears 

 but little resemblance to these forms. 



From R. greppini (Opp.) in Till (pi. vi, figs. 4-7) the form here 

 described is distinguished, by its smaller umbilicus. Dr. Till does 

 not give the measurements ; but, according to his figure, the um- 

 bilicus equals about 44 per cent, of the diameter, not 40 as in my 

 specimen : the section also is too thin near the periphery. On the 

 other hand, there is very close agreement in the ornament. The 

 characteristic concave shape of the primary costse, leading up to 

 the radially elongated spine at the point of bi- or trifurcation, is 

 very distinctive, just as in my specimen ; whereas R. Jiungarica 

 Till, the commonest form at Villany, has primaries which are 

 raised into a sharp crest at the middle, not at the end of the 



