Notices of Memoirs — Prof. T. R. Jones — Fossil Phyllopoda. 41 



as usual, much more apparent in the quartz than in the felspar, and 

 beautiful examples of '"strain-shadows" may frequently be seen in 

 those quartz areas which have not yielded altogether to the pressure. 

 A further stage in the process is reached when the sei'icitization of 

 the felspar has proceeded so far as to permit of the " shoving apart" 

 of the fragments by the various forces which have acted in bringing 

 about the degradation of the whole rock mass. This gradual decora- 

 position of the felspar and movement of the rock constituents can be 

 perfectly traced in the series of thin sections examined until the 

 rock cannot be distinguished from an ordinary arkose, while the 

 arrangement on the large scale, and the more or less parallel 

 alignment of rounded and waterworn quartzose fragments, amply 

 testify to the final assortment and rearrangement of the disintegrated 

 material as a result of ordinary sedimentation. 



The relations between this granite and arkose are of rather 

 unusual scientific interest, showing, as they do, the Pre-Huronian 

 existence of a basement or floor upon which these sediments were 

 laid down, and which in this portion at least has escaped the 

 movements to which the Laurentian gneisses have been subjected. 

 The granite is also somewhat different, both in composition and 

 appearance, from the granites and gneisses classified as Laurentian, 

 and which are so frequently referred to as the Fundamental Gneiss 

 or Basement Complex, although during recent years the assumption 

 implied in these terms has been considerably weakened by the fact 

 that the contact between such rocks and the associated elastics is, 

 wherever examined, one of intrusion. On the other hand, the 

 composition of the Huronian strata furnishes indubitable evidence of 

 a pre-existing basement or floor essentially granitic in composition, 

 while the abundance of red granite pebbles and fragments, which 

 are so pre-eminently abundant in the breccia-conglomerate lying at 

 the base of the Huronian system, are very similar in composition and 

 appearance to the granite desci'ibed above. This granite is, therefore, 

 regarded by the authors as the only instance at present known in 

 which the material composing the Huronian elastics can be clearly 

 and directly traced, both macroscopically and microscopically, to the 

 original source from which it has been derived. 



in. — The Fossil Phyllopoda of thk Paleozoic Eocks. Thirteenth 

 Eeport of the Committee, consisting of Professor T. Wiltshire 

 (Chairman), Dr. H. Woodwakd, and Professor T. Pupert Jones 

 (Secretary). (Drawn up by Professor T. Rupert Jones. )^ 



§ I. 1889-1892. Anomalous Silurian Phyllopods (?) from 

 Germany and America. — In the Sitz.-Ber- Gesell. nnlarf. Freunde 

 zu Berlin, 1890, p. 28, Dr. A. Krause described a small fossil 

 carapace of doubtful alliance, but possibly related to the Phyllopods, 

 frcmi the North-German gravel of Scandinavian Bez/j^'c^m -limestone 

 (Upper Silurian). In the Zeitscli. Detitsch. Geol. Gesell., vol. xliv, 

 1892, p. 397, pi. xxii, figs. 19 a-c, Dr. A. Krause redescribed 

 and figured this anomalous little fossil. 



1 Kead before the British Asiociation, Section C (Geology), Toronto, 1897. 



