300 
INFERIOR OOLITE AMMONITES. 
of the specimens nothing definite can be said about the ventral area, but, 
judging from a broken specimen with its edges ground down, the carina and 
sulci appear later than the second row of spines ; but the details are very obscure. 
From Zurcheria generally the genus Haplopleuroceras is distinguished by its 
two rows of spines, and its sulcate-carinate ventral area ; but from Zurcheria 
pugnax the latter character alone separates it. From " Pleuroceras " it is really 
not distinguished by any feature except that the carina is only very feebly 
crenulate ; but, in any case, the name " Pleuroceras " is invalid from prior use 
(see p. 288, foot-note 2). 
As defined at present the genus Haplopleuroceras only contains two species, 
which both occur in the Goncavum- zone. 
Haplopleueoceeas sdbspinatum, 8. Buchman. Plate XLIX, figs. 5, 6 ; Plate LI, 
figs. 1—10 (13—15?). 
1881. AMALTHEtrs STTBSPINATUS, S. Buckman. Inf. Ool. Ammonites ; Quart. 
Journ. G-eol. Soc, vol. xxxvii, 
p. 606. 
1883. — — — New Ammonites ; Proc. Dorset 
Field Club, vol. iv, pi. ii, 
figs. 1 a — c. 
1889. Pletjeoceeas subspinatttm:, 8. Buchman. Descent of Sonninia, &c. ; 
Quart. Journ. Geol. Soc, 
vol. xlv, p. 657. 
Discoidal, compressed, very evolute, sulcate-carinate. Whorls almost quadrate, 
ornamented with prominent, somewhat distant, sharp-edged, direct ribs, inclined 
laterally and ventrally; and on each rib are situated two spines, one near the 
inner margin, and one on the border of the lateral and ventral areas. Yentral 
area broad, squared, divided by a conspicuous, sometimes slightly-crenulate 
carina, on each side of which travels a well-marked furrow; ventral area also 
ornamented by well-marked forward-projected ribs dipping into the furrows, where 
they disappear, but pass over the carina as strife. Inner margin not defined, 
steeply sloped, with less conspicuous ribs, slightly twisted forwards. luclusiou 
almost nothing. Suture-line : — siphonal lobe shorter than superior lateral ; superior 
lateral saddle deep ; inferior lateral lobe small and rather elevated. 
This is one of the handsomest and most distinct of Inferior-Oolite species. 
There is no chance of its being confounded with any of its British contemporaries 
in fact, so much is it unlike Inferior-Oolite fossils that I have noticed it in 
Museums labelled as a Liassic species ; and the dark colour of certain examples is 
no doubt deceiving. 
