XV.] CAMBRIAN AND SILURIAN IN EUROPE. 365 



In connection with this history it may be mentioned that in 

 March, 1845, Sedgwick presented to the Geological Society a 

 paper on the Comparative Classification of the Fossiliferous 

 Rocks of North Wales and those of Cumberland, Westmore- 

 land, and Lancashire ; which appears also in abstract in the 

 same volume of the Geological Journal that contains the ab- 

 stract of the essay and the map just referred to. (I. 442.) 

 That this abstract also is made by another than the author is 

 evident from such an expression as "the author's opinion 

 seems to be grounded on the following facts," etc., (p. 448) and 

 from the manner in which the terms Lower and Upper Silurian 

 are applied to certain fossiliferous rocks in Cumberland. Yet 

 the words of this abstract are quoted with emphasis in Siluria 

 (1st. ed., 147), as if they were Sedgwick's own language recog- 

 nizing Murchison's Silurian nomenclature.* 



II. MIDDLE AND LOWER CAMBRIAN. 



Investigations in continental Europe were, meanwhile, pre- 

 paring the way for a new chapter in the history of the lower 

 palaeozoic rocks. A series of sedimentary beds in Sweden and 

 Norway had long been known to abound in singular petrifica- 

 tions, some of which had been examined by Linnaeus, who 

 gave to them the name of Entomolithi. They were also studied 

 and described by Wahlenberg and by Brongniart, the latter of 

 whom, from two varieties of the Entomolithus paradoxus, Linn., 

 established in 1822 two genera, Paradoxides and Agnostus. 

 In 1826 appeared a memoir by Dalman on the Paleeadse, or 

 so-called Trilobites; which was followed, in 1828, by his 

 classic work on the same subject. (Uber die Palaeaden oder 

 so-genannten Trilobiten, 4to r with six plates, Leipsic.) In 

 these works were described and figured, among many others, 

 two genera, Olenus, which included Paradoxides, Brongn., 



* [A letter to the author, written him by the late Professor Sedgwick after 

 reading the above, confirms the opinion here expressed. The abstract in 

 question was furnished by Murchison himself to the Geological Society, 

 the secretary of which declined to receive the abstract offered by Sedgwick of 

 his own paper.] 



