454 Notices of Memoirs — British Association — 



coal-field of whicli the Notts and Derbyshire area is merely an 

 extension. 



In fact, it seems probable that the habit of collectors to look for 

 fossils only in the Coal-measure shales, to the neglect of the ironstone 

 nodules, may account for the paucity of specimens found in other 

 coal-fields. 



The other species, Palceoxyris <?ff/-Jo«fln«(Schimper) and Palceoxi/ris 

 prendeli (Lesq.), seem, on the contrary, to be extremely rare in this 

 area, and, when found, they are usually associated with quantities 

 of P. helicter aides. 



Vetacapsula cooperi (Machie & Crocker) ^ must still lay claim to 

 being an extremely rare fossil. This genus is not restricted to 

 a definite horizon in Derbyshire and Notts Coal-fields, but has been 

 found to range from between the Waterloo and Ell Coals at Newthorpe 

 Claypit, downwards to the Kilburn Coal at Loscoe Colliery. Three 

 new specimens have been obtained — two from the Silkstone Coal and 

 one from the Kilburn Coal. One of these, a specimen from the 

 Silkstone Coal of the Calow Colliery, Chesterfield, shows a feature of 

 great interest. When first found the fossil presented the appearance 

 of a very much crushed example ; but careful development revealed 

 the fact that the fossil was, in reality, a perfectly normal flattened 

 specimen, and the feature that gave rise to the apparent deformity 

 was the presence of a medial, longitudinal flange, or fin-like structure, 

 which extends along the ' median raphse ', emphasized by the original 

 describer of the genus, dismissed in my former paper as possibly due 

 to crumpling, and again brought into prominence by Mr. J. Wilfred 

 Jackson. It seems now that this ' median raphse ', which appears to 

 be a constant feature in every specimen recorded, may be caused in 

 the ordinary specimens by this flange being torn off, and being left 

 embedded in the matrix of the counterpart. It is also instructive 

 to compare this new-found flange with that described by Mr. Bashford 

 Dean on the egg-case of Chinmra coUei. 



From the examination of the four specimens in the author's 

 collection and others elsewhere it is becoming more apparent that 

 there are two distinct species included under the name of Vetacapsula 

 cooperi. Owing, however, to the at present uncertainty as to their 

 affinities, and to the rarity of their occurrence, it seems best still to 

 keep them under one trivial name and separate them by applying the 

 designation ' forma a ' to those specimens in which the pedicle 

 expands suddenly into the body, forming a distinct shoulder in the 

 lower third of the body and giving rise to a ' deformity ' or crumpling 

 in that region ; and the designation ' forma /3 ' to those in wliich the 

 pedicle expands more gradually into the body, giving to the specimen 

 an ovate contour, with the ' deformity ' or crumpling in the centre. 



A curious and interesting feature is seen on the outer edge of all 

 specimens conforming to 'forma ji\ Just before the body contracts 

 to form the beak there is found, by examination with the ordinary 

 lens, a minute crenulation or crimping of the edge of the fossil, which 

 may be compared with the markedly rugose lateral webs seen on the 

 egg-cases of Chimcera collei, Khinocliimcera., and other Chimaeroids. 



^ E. J. Machie, Geol. and Nat. Hist. Repertory, vol. i, pp. 79-80, 1865-7. 



