4:4:4: 



ME. J. F. .TACKSOX OX 



[yoI. lixviii^ 



HemeriB. 



Strata and Fauna. 



Feet inches,^ 



1827, 5191 (4 ex.), Somccovliynclna acuta (large) ; 

 5156, Fiircirhi/ncliiafurcata S. B. ; 5192, JE'riono- 

 rhynchia serrata ; ol9o, P. qtiinqueplica fa : 5157 

 (2ex.), Quadratirhynchia cf.crassimedia S. Buck- 

 mau : 5196, StoJmorhyncliia cf. hothenhampton- 

 ensis; bVdl, S.houcliardi ; 5192 a, Si'dirhynchia 

 (?) ^•p.=jRhynchonella fall ax (Deslongcliamps) 

 Walker, but presumably new ; 5194, JRiulirhyn- 

 cJiia ? cf. Terehratida triplicata fronto Quen- 

 stedt : 5160, Lohothyris punctata ; 1845, Zeilleria 

 cornuta ; 1844, Z. afF. cornuta; 5343, Z. cf. 

 quad/'ifida: 5161, Z. sp._ 



Apparently transitional from 

 Spinatum. E. Rough conglomeratic 'marlstone,' with large irre- 



gular coricretious of calcareous sandstone at the 

 base. WiynclioneUa ' tetraedra,' JRh. spp., Tere- 1 

 hratida punctata, Zeilleria sp., Spiriferina 



^ sp., etc. 4-6^ 



[3726, Tetrarhyncliia media tetraedra ; 4956, 

 Quadratirhynchia aff. crassimedia ; 5359, 

 Q. crassimedia sphceroidalis ; 4523, Q. atl". sphce- 

 roidalis; bVd9, Lohothyris punctata ; 4951,i.S7«ft- 

 punctata ; 1843, 5190, Aulacothi/ris florella; 

 1838, 52ul, Zeilleria mariee : 5202, Z. suh- 

 numismalis; 5200, an inverted Terebratulid (gen. 

 nov.) ; 5331, Spiriferina oxygona (Davidson); 

 1841, 5158, Sp. sp. like oxygona Davidson, but 

 witli a costate fold; 1840, Sp. sp. (smooth) — cf. 

 Spirifer rostratus Davidson,Mon.Brit. Ool. Lias. 

 Brach. Ill, 1851, ii, 3.] 



The presence o£ Hccrpoceratoides and the ahsence of Palto-^ 

 pJeuroceras indicate that at least the upper portion of layer X^ 

 belongs to the 'Upper Lias.' The date of the lower portion of X^ 

 is very doubtful ; no fossils of zonal importance were observed, and 

 there are only very obscure indications of any break at the base. 



The presence in the serrata bed of a large Harpoceratoid bearing 

 a superficial resemblance to Harpoceras f'alciferiim is of some 

 interest, in that it enables us to understand how early observers 

 cam.e to record ^Ammonites serjyeiifinus,' etc., from the 

 ' marlstone ' portion of the Junction-Bed. Xo real credence can 

 be given to the alleged occurrence of tyjjical ' ITpper Lias ' species 

 in the ' marlstone." 



PleurotomaricB occur in the serrata bed, but no indication of 

 any definite '■ JPIev.rotomaria Bed' was observed. 



The brachiopoda are the most abundant fossils of the two. 

 ' marlstone ' layers. ShynchoneJla serrata is fairly common in 

 the serrata bed, to which it would appear to be confined. Large 

 specimens of RliynclwneUa acuta, often in a fine state of preser- 

 vation, are common in the serrata bed; ^li. acuta is very much 

 rarer in the basal ' marlstone " layer, so much so that an abundance 

 of that form in a block is strono-lv suo-o-estive of the serrata bed. 

 JR.li. acuta is markedly rare at Down Chff, where the serrata bed is. 

 considered to be absent. 



Section YII was meastu'ed in situ near the eastern end of' 

 Thorncombe Beacon, only a short distance east of the position from 

 which the block measured in Section YI must have fallen. It 



