12 BRITISH OOLITIC AND LIASIC BRACHIOPODA. 



Mr. Walton and Mr. Pearce, of Bath, as well as numerous specimens collected by myself, 

 have enabled me to note the extreme variations exhibited in its general form and shape of 

 the muscular impressions. Sometimes these impressions project in the prominent manner 

 shown by figs. 4, 6, 8, while at other times they are barely distinguishable ; in one speci- 

 men, belonging to Mr. Pearce, the whole four, where actually depressed, producing a remark- 

 able concavity in the valve. Mr. Pearce was at first disposed to consider these specimens 

 as examples of the upper valve, an opinion, however, he afterwards relinquished ; and, 

 curiously enough, although many hundreds have been collected by Messrs. Walton and 

 Pearce, they have not been able to obtain the upper valve in any one instance. 



This species was originally discovered by the Rev. H. Jelly, who applied to it the 

 specific appellation " Antiquior," but no figure or description appeared before May, 1847, 

 when I described and figured it in the London Geological Journal, the only published 

 record respecting it being the insertion of this name in Mr. Morris's valuable Catalogue 

 of British Fossils, in 1843. 



The Crania Antiquior is found in the great Oolite of Hampton Cliff, near Bath ; the 

 specimens figured are from the collection of Mr. Walton. 



All the figures are of natural size, except fig. 8, which is enlarged. 



6. Crania Moorei, Dav. Plate I, fig. 9. 



Diagnosis. Shell irregular, transversely oval, suborbicular, truncated posteriorly; 

 upper valve convex and slightly conical, with the vertex near the centre ; surface smooth 

 and punctuated ; interior presenting four muscular impressions, the posterior ones slightly 

 marked, as well as the anterior two, which are arranged in the form of a V. The digitated 

 genito-vascular impressions hardly visible ; interior closely punctuated. Length and 

 breadth about 1 line. The upper valve only is known. 



Ohs. This small species was found by Mr. Moore, in the upper lias, near Ilminster ; 

 its position is higher than that of those beds containing the Leptcenas in the same locality. 

 The figure is drawn from a specimen kindly given to me by Mr. Moore, and I take great 

 pleasure in naming the species after him. 



Plate I, fig. 9, natural size. Fig. 9, «, b, enlarged. 



Genus — Thecidea, Lefrance. 1828. 



Shell unequivalved, thickened, more or less irregular ; largest valve partially or entirely 

 attached by its own substance, or, when young, in some species by a peduncle issuing 

 from the extremity of the beak to submarine bodies ; form longitudinally or transversely 

 oval, sometimes subquadrate ; upper valve small, more or less convex, smooth, or other- 



