SOME NEW SPECIES OF AMMONITES. 143 



LYTOCERAS CONFUSUM, S. 8. BucL, plate iii., figs. 1 and 2. 



1881. LTTOCEEAS CONFUSUM, 8, 8. Buchnan, Quart. Jour., G-eol. Soc., page 

 601, vol. 37, No. 148. 



Whorls not numerous, increasing quickly in width. Inclusion 

 very small. Ornamentation, numerous fine waved lines. Mouth 

 border a plain bend, produced on the ventral area. Inner por- 

 tion of whorl very square and straight ; in adult specimens be- 

 coming more marked, but in very young ones scarcely so at all. 

 Aperture sub-triangular, with the ventral area rounded. 



The specimen figured was really only a centre from a big 

 specimen trimmed up ; but it shews all the characteristics of the 

 species, and was more convenient as regards size. The figure 

 is two-thirds the size of the original, which has the test very 

 well preserved. In very large adult specimens, which some- 

 times measure as much as 17 inches across, the aperture is more 

 angular, being almost equilateral triangular, with rounded 

 edges, and the peculiar squareness and straightness of the inner 

 portion of the whorl becomes very marked. 



The figure ii. a shews a young specimen natural size, with a 

 portion of the mouth-border, which is quite plain. 



Localities. Bradford Abbas and Half-way House, Dorset, 

 fairly abundant. 



Position, zone of Harpoceras Sowerbyi. 



Nearest Allied Form. Lytoceras jurense (Zieten), from the 

 Upper Lias Sands, by which name this species was often 

 quoted from Dorset. Lytoceras confusum, however, differs from 

 it in having a greater number of whorls, somewhat less inclu- 

 sion, its peculiar shaped aperture, and very square dorsal area 

 of whorl, also rather more complicated suture-line. 



HAPLOCERAS ETIIERIDGII, Nolis., plate iii., fig. 3 a-b. 



. Shell somewhat compressed. Whorls broad. Inclusion about 

 one half. Ornamentation, rather stout rounded ribs, very slightly 

 waved, traversing about two-thirds of the side. Dorsal area 



