202 INFERIOR OOLITE AMMONITES. 



This species occurs at Coaley Wood in the Dispansum-heda (Juo'ense-zojie),'but I 

 have only small examples. Plate XXXIV, figs. 6, 7, gives two views of a specimen 

 which is none too well preserved. 



Geammoceras subquadratum, 8. Buchnan. Plate XXXVI, figs. 3, 4, 5. 



1887. Ammonites (Hildoceeas) qtjadbatus, Denchmann (non Haug). Fauna 



von Dornten ; Abh. der geol. 

 Specialkarte, &c., Bd. viii, Heft 2, 

 pi. vi, fig. 3 ; pi. X, fig. 6. 



Discoidal, hollow-carinate. Whorls slightly compressed laterally, ornamented 

 with rather strongly-reflexed, subarcuate ribs. Ventral area broad, carrying a 

 strong hollow carina. Inner margin steep, smooth, and broad. Inclusion about 

 one-third. Umbilicus rather deep, whorls slowly coiled. 



I have only seen this one example ; but, although it may be regarded as some- 

 what intermediate between Gramm. quadratum and Gramm. Sseynanni, yet it 

 possesses some peculiar and distinct characters, which have induced me to 

 separate it provisionally as a distinct form. 



From Dumortier's figure of Gramm. quadratum it may be easily separated by 

 its almost inconspicuous ventral furrows — more conspicuous carina — broader 

 whorls — deeper umbilicus, with well-defined inner margin — and, finally, by the ribs 

 being more strongly reflexed, forming larger curves on the outer area. From a 

 form of Gramm. Sseman7ii, which I have had depicted on the same plate (figs. 

 6, 8), Gramm. suhquadratum differs by its coarser, more reflexed ribs — by its 

 stronger inner margin, caused by the greatest thickness of whorl being on the 

 edge of the margin (figs. 5 and 8), and by its deeper umbilicus with a greater number 

 of whorls, that is, more slowly coiled. 



Gramm. suhquadratum appears to agree with the specimen depicted by 

 Denckmann, except that it is a trifle smaller-centred. Denckmann's figure also 

 shows more conspicuous sulci at the top of the aperture ; but it almost appears as 

 if this were an error in drawing, because the sulci are not shown like this in the 

 lower part of the whorl. 



Probably Denckmann's figure represents a form intermediate between Gramm. 

 quadratum (Dumortier's figure) and my suhquadratum. Such a form is, of course, 

 to be expected, and the separation of Gramm. subquadratum from Gramm. 

 quadratum on the one hand and Gramm. Ssemanni on the other, is more or less 

 arbitrary, and for the sake of convenience. 



