TRANSACTIONS OF SECTION C. - 613 



Dr. Vaughan finds closely resembles a form (P. aff. scabriculus, Mart.) abundanl 

 in the Avon section and elsewhere at the top of the Dibunophyllum Zone. 



Finally, a consideration of the thicknesses and characters of the sedimentary 

 series and of the outcrops of dolerite shows that earth movements along a 

 N.E.-S.W. line have made themselves felt during — 



(1) Upper Old Red Sandstone and Lower Carboniferous times ; and 



(2) Some period between Lower Carboniferous and Coal Measure times. 



(This movement has resulted in the unconformity between the ' Mill- 

 stone Grit' and the Coal Measures.) 



And further that the dolerite came up through several passages, some of whicb 

 form a linear series having approximately the same trend. 



6. Structural Petrifactions from the Mesozoic, and theii bearing on Fossil 

 Plant Impressions. By Miss M. C. Stopes, D.Sc, Ph.D., F.L.S. 



This paper dealt with the importance of the structural petrifactions in the 

 Carboniferous — e.g., exposure of the true nature of so many supposed 'ferns'; 

 with the need of similar petrifactions from beds of Mesozoic age ; and the 

 danger of inferences drawn from plant impressions — e.g., untrustworthmess of 

 many of Heer's and Ettingshausen's systematic determinations. 



The discovery of true petrifactions in the Cretaceous, the nature of the flora ' 

 contained in the nodules, and unusual points in its composition were considered. 

 Special illustrations of its interest are : Yezonia, a new type of which the ex- 

 ternal appearance gives no clue to its nature ; Hie discovery of the first-known 

 flower with its anatomy petrified; and of the internal anatomy of the leaves of 

 Xihsonia, long well known as impressions. 



7. On some Rare Fossils from the Derbyshire and Nottinghamshire Coalfield. 

 By L. Moysey, B.A., M.B., B.C., F.G.S. 



In the temporary museum in connection with this section there will be found a 

 collection of fossils illustrating some of the rarer forms of the Coal Measure fauna 

 obtained during the last eight years from this district. From these it has been 

 thought desirable to select some, mainly fragmentary specimens, for more detailed 

 description, in the hope that they may be of assistance in the identification of other 

 more perfect specimens, should such be obtained, and that a discussion on their 

 more perplexing features may lead to a more definite idea as to their affinities. 



Specimen 1, from Shipley, near Ilkeston, Derbyshire. — These minute bodies. 

 about 3 mm. long, are evidently the valves of the carapace of a phyllopod. 

 A similar fossil was described by Lea 1 from Pennsylvania under the name of 

 Cypricardia leidyi. Dr. T. Rupert Jones 2 gave it the name of Leaia leidyi, and 

 described (wo varieties, one L. leidyi var. Williamsoniana, from Ardwick, near 

 Manchester, and the other L. leirh/i var. Salteriana, from Cottage Row. Crail, 

 Fifeshire. The present example agrees fairly closely with the Fifeshire specimen ; 

 but, on the whole, it seems best to create a new spei ies for it, Lrain trigonoides 

 sp. now, rather than risk confusion by adding a varietal appellation. 



Specimen 2, from Shipley, is of interest, owing to the great difficulty of its 

 interpretation. Possibly the best explanation is that it is the glabellar region 

 of a Prestwichia. The presence of two minute crescentic dots, one on each side 

 of the median line, is in favour of this theory, on the assumption that they are 

 the larval eyes of the animal. Dr. Henry Woodward, however, who has examined 

 this specimen, is very doubtful as lo its lemuloid origin. 



Specimen 3, from the Kilburn Coal, Trowell Colliery, Notts. — This has also 

 been seen by Dr. Henry Woodward, who thinks it may he the terminal segments 

 of a macrourous decapod, and may lie allied to Pygocephalus. The curious 

 feature in this specimen is the presence of crescentic openings on each segment 



1 Proc. Acad. Nat. Sc. Philadelphia, 1855, vii.. p. 341, pt. 4. 

 " Man,. Pal. Soc, 1862, Appendix, p. 115, Plate 1.. fig. 21. &c. 



