po HISTORICAL PALAEONTOLOGY. 



branches, which are united in a net-like manner by numerous 

 delicate cross-bars, and exhibit a row of little cups or cells, in 

 which the animals were contained, on each side. Dictyonema 

 has generally been referred to the Graptolites; but it has a much 

 greater affinity with the plant-like Sea-firs (S ' ertularians) or the 

 Sea-mosses (Polyzoa}, and the balance of evidence is perhaps 

 in favor of placing it with the latter. 



LITERATURE. 



The following are the more important and accessible works 

 and memoirs which may be consulted in studying the strati- 

 graphical and palaeontological relations of the Cambrian 

 Rocks : 



(1) 'Siluria. ' Sir Roderick Murchison. 5th ed., pp. 21-46. 



(2) 'Synopsis of the Classification of the British Palaeozoic 



Rocks. ' Sedgwick. Introduction to the 3d Fasciculus 

 of the ' Descriptions of British Palaeozoic Fossils in the 

 Woodwardian Museum, ' By F. M'Coy, pp. i-xcviii, 



(3) ' Catalogue of the Cambrian and Silurian Fossils in the 



Geological Museum of the University of Cambridge. ' 

 Salter. With a Preface by Prof. Sedgwick. 1873. 



(4) ' Thesaurus Siluricus. ' Bigsby. 1868. 



(5) " History of the Names Cambrian and Silurian. " Sterry 



Hunt. ' Geological Magazine. ' 1873. 



(6) ' Systeme Silurien du Centre de la Boheme. ' Barrande. 



Vol. I. 



(7) 'Report of Progress of the Geological Survey of Canada, 



from its Commencement to 1863, ' pp. 87-109. 



(8) 'Acadian Geology.' Dawson. Pp. 641-657. 



(9) "Guide to the Geology of New York," Lincklaen; and 



" Contributions to the Palaeontology of New York, " 

 James Hall. ' Fourteenth Report on the State Cabinet. ' 

 1861. 



(10) 'Palaeozoic Fossils of Canada.' Billings. 1865. 



(n) 'Manual of Geology.' Dana. Pp. 166-182. 2nd ed. 

 1875- 



(12) "Geology of North Wales," Ramsay; with Appendix on 



the Fossils, Salter. ' Memoirs of the Geological Sur- 

 vey of Great Britain, ' vol. iii, 1866. 



(13) "On the Ancient Rocks of the St. David's Promontory, 



South Wales, and their Fossil Contents. " Harkness 

 and Hicks. ' Quart. Journ. Geol. Soc., ' xxvii. 384- 

 402. 1871. 



