594 



S. S. BTTCKMAN ON AMMONITES PROM 



7. Termination like 'No. 6, but not produced on ventral area. 



Cosmoceras subfurcatum (Schloth.). \ Oosmoceras Caumoutii (cPOrb.). 



8. Termination, a spathulate ear each side, and one on the ventral 

 area. 



Ammonites cadomensis, Defrance. 



9. Termination, a plain single bend, more or less produced on 

 ventral area. 



Amaltheus spmatus (Eruguiere) in the Lias. 

 Inf. Oolite. Amaltheus subspinatus, S. S. Buchn. 



Lytoceras confusum, S. S. Buckm. 



We will now proceed to give a short notice of the various species 

 of Ammonites recognized in this district. 



STEPHANOCERAS HlJMPHRIESIANUM (Sow.). 



1825. Ammonites Humphriesianus, Sow. Min. Conch, pi. 500, 

 middle figure. 



1830. A. Humphriesianus (Sow.), Zieten, Petref. pi. 67. fig. 2. 



1845. A. Humphriesianus (Sow.), d'Orb. Pal. Franc. Terr. Jurass. 

 pis. 133, 134, 135. figs. 1, 2. 



1849. A. Humphriesianus (Sow.), Quenstedt, Ceph. tab. 14. 

 figs. 7, 11 ; Quenstedt, Jura, pi. 54. figs. 2, 3, 4. 



1849. A. coronatus oolithicus, Quenstedt, Ceph. tab. 14. fig. 4. 



1856. A. Humphriesianus (Sow.), Oppel, Juraformation, p. 376, 

 no. 40. 



1856. A. subcoronatus, Oppel, Juraformation, p. 376, no. 39. 



1856. A. Bayleanus, Oppel, Juraformation, p. 377, no. 43. 



1854. A. Humphriesianus (Sow.), Morris, Catalogue, p. 292. 



1878. Stephanoceras Humphriesi (Sow.), Bayle, Explic. de la 

 Carte Geol. de la France, vol. iv. pi. 51, figs. 2, 3. 



1881. A. Humphriesianus (Sow.), J. Buckman, Quart. Journal 

 Geol. Soc. vol. xxxvii. p. 65, fig. 6. 



Bayle in ' Explication de la Carte Geologique de la France,' vol. 

 iv. plate 51. figs. 2, 3, shows what I take to be a rather peculiar 

 variety of Stephcuioceras Humphriesianum. 



Localities. Oborne, and near Sherborne, Burton Bradstock, and 

 other places : rather common. 



Quenstedt, under the name of Amm. coronatus oolithicus, figured the 

 young form of the thick variety of this species, which Oppel also 

 mentioned by the name of subcoronatus. Oppel also separated the 

 thin form, under the name of Bayleanus, observing that it occurred 

 lower than Humphriesianus proper. My own observations, however, 

 do not agree with this, as I have found both the thin and thick 

 varieties together ; and Mr. D. Stephens assures me that they both 

 occur together at Milborne Wick, the thin variety being the com- 

 moner. I have, however, seen the necessity for distinction, and 

 have kept Oppel's names for the varieties, the thick variety being 

 Steplian. Humphriesianum, var. subcoronatum (Oppel), and the thin 

 JStephan. Humphriesianum, var. Bayleanum (Oppel). 



