xlviii INFERIOR OOLITE AMMONITES. 



Locality and Stratum. — Dorset : Mapperton, near Bearninster, evidently from 

 near the base of the Inferior Oolite limestone. 

 Date of Existence. — Murchisonse hemera. 



2. Ancolioceras substriatum, 8. Buchnan. SuppL, Plate VI, figs. 14 — 16. 



Description. — Platyleptogyral, snbconcavumbilicate, laterally subflexicostate 

 passing into substriate. 



Remarks. — In the costate stage the ornament is, in design, similar to that of 

 the previous species, only the bulla has lengthened out into a rib. In degree it 

 is less, and it changes rather quickly to what is little more then a striate stage. 

 In this stage there are not the intermittent bulges seen in Lioceras. As this 

 species is the homceomorph of Lioceras bifidatum, and as cariniferum is less 

 developed than L. uncinatum, it may be surmised that there are at least three 

 species separating this one from the last — forms corresponding to vncinntum, 

 uncum, and gracile. 



Locality and Horizon. — Dorset : Stoke Knap, in the " Bottom Bed," as the 

 quarrymen term it — the bed below the "Building Stone." 



Date of Existence. — Murcliisonse hemera. 



3. Ancolioceras ? costatum, 8. Buchnan. Plate VII, fig. 7; Plate A, fig. 11; 



Suppl., Plate XVII, fig. 30. 



1888. Lioceeas ambiguum, var. costatum, This Monogr., PI. vii, fig. 7 : 1889, 



PI. a, fig. 11. 



Description. — Platyleptogyral, excentrumbilicate, parvi-subdensi-flexicostate. 



Note. — In connection with the excentrumbilication the periphery becomes 

 broader, more rounded, and less carinate. 



Remarks. — The radial curve is similar to that of Ancol. cariniferum and sub- 

 striatum, there being a rather long peripheral projection. There are, however, 

 differences in points of detail in regard to the radial curve, costation,. mode of 

 growth, &c, which make the generic association doubtful. 



Distinction. — Prom substriatum, character of costation, absence of striate stage. 



Locality and Stratum. — Somerset: Haselbury, near Crewkerne, in the beds of 

 the " lower division." ' 



1 See Hudlestor, ' MoLogr. Gasteropoda,' p. 41. The species is probably from the first or second 

 bed of the lower division. 



