39tL me. s. s. buckmax ox [vol. Ixxviii, 



MhynchoneUa houchardi {StolmorJii/ncJiiff spp.). As Sh. hou- 

 chardi was, according to Moore, of post Saurian-bed date, this 

 seems to show that the serrata bed and the houchardi bed were 

 being destroyed together, and that some of their fossils were being 

 mixed up. The serrata bed holds evidence of such a mix-up, for 

 in this same block were RhynchoneUa {Homoeorliynchia) acuta, 

 the large form, Quad ratirliy ncli ia crassimedia,^ Q. aff. sjplKjeroi- 

 dalis,- and other species which properly belong to the lower bed — 

 the brown m.arlstone. I have seen RhynchoneUa acuta in the 

 Vpper Lias part of the Junction-Bed. 



For successful collecting, it is important to note the distinction 

 in matrix between the pale, rather soft serrata bed and the dark 

 hard Marlstone below, as it is of little use to look in the latter for 

 the special fossils of the former. The hard Marlstone is a fairly 

 constant bed at the base of blocks of Junction-Bed : the serrata 

 bed is rarely found, having been denuded from the Marlstone 

 before the Upper Lias was cemented to it. The planed-off top of 

 the Marlstone shows the denudation : it is also a guide as to 

 which is the upper part of odd Marlstone blocks. 



However, this lower ]\[arlstone is not necessarily homogeneous, 

 and may be compounded of beds of various dates. In my former 

 paper I mentioned my lack of success in finding Day's Fleuro- 

 tomaria Bed.3 During my visit in 1920 I was successful. A 

 Marlstone block about 1 foot thick gave the following : — 



(fi ) Hard, finely ironshot, blue marlstone decomposing to a rusty brown, 

 about 3 or 4 inches. 



(b) Hard ironshot in the middle of the bed. 



(c) Hard ironshot in the lower part of the bed, enclosing- big blue sand- 



stone-pebbles ; they look like fragments of the Starfish-Bed. See 

 later, p 397. 



The following is a rough sketch of the faunal contents : — 



Upper 3 or 4 inches — Pleurotomaria spp. Specimens so crowded that, in 

 the course of the extraction of one, others were broken. Mainly acuminate 

 species, but one or two more depressed. See p. 400. 



Just under the Pleurotomarise various species of Paltoplev.roceras and 

 Quadratirliynchia crassimedia occur. 



In about the middle of the block a fragment of Ammonites cf. Jcurnanus 

 Oppel and various lameEibranchs were found. 



In the lower part of the block, a dei^ressed Pleurotomaria was seen. 



In another small block — a rather soft brown matrix, quite 

 unfamiliar — I found a single small example of another inverted 

 Terebratulid : it is like Terehratula hakeriad Davidson, which 

 comes from the acutuni bed (Transition-Bed) of Xorthamptonshire, 

 but very rarely, only two or three specimens being known. "^ 



1 I, 6, pi. xiii, fig. 3 a. - I, 6. pi. xiii, fig. 2. -^ I, 5, p. 83. 



"* Its rarity may be due to the fact that it really comes in the bottom layer 

 of the Transition-Bed — the athleticum horizon, which has been almost 

 destroyed in Xorthamj^tonshire. The finding of a like form in the Junction- 

 Bed supports this idea, for Tiltoniceras has not been foimd in this bed, 

 although there are evidences of the athleticum fauna. 



