06 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



Description of the first sioc Tables. 



I have in this oldest Cambrian series (from the Longmynd rocks 

 to the Upper Tremadoc) given an analytical table for each of the 

 6 formations or groups of strata. They cannot be otherwise tho- 

 roughly comprehended, taken as a whole, without wearisome de- 

 scription, owing to the non-representation of some classes, and 

 the unequal representation and distribution of others. Neverthe- 

 less I have constructed Table No. VII. for the whole, to show 

 the unequal distribution, the Table delineates every thing, its 

 accuracy being tested through the six smaller tables (Nos. I. to 

 VI.), wherein are given the analyses of all the groups sepa- 

 rately. More than this, these six small tables enable the student 

 to see immediately the numerical value of each division, and the 

 number of species that pass up or live on to the succeeding period 

 or formation. Again, there is much difficulty in following some 

 authors through the many subdivisions and local names adopted by 

 them for the strata between the Longmynd group and the close 

 of the Upper Tremadoc. The succeeding Arenig, in which some of 

 the classes are largely represented, while the formation is widely dif- 

 fused geographically, enables me to show the distribution in one 

 Table (No. VIII.); the same is also done for every succeeding epoch. 



The Longietnd and Harlech Groups. — Table I. enumerates 

 the fauna of the Longmynd and Harlech beds only, chiefly those 

 of St. David's, and the first traces of life in the British Islands. 

 In this Table 8 if not 9 of the 14 classes have no representa- 

 tives, no species of them having as yet occurred ; and, with the 

 exception of the Crustacea, the remaining 5 classes are but feebly 

 illustrated. This Table, however, at once lays bare the fact that we 

 are not tabulating the commencement of life even in our own area ; 

 both the rock masses and the fossils that do occur, notably the great 

 Paradoxides, bid us search still deeper in time for their ancestors as 

 well as those of the pelagic Mollusca, as also of the Brachiopoda 

 (Lingulctz, Obolellce, and others). All these and the Lyssakine hexac- 

 tinellid sponges had their progenitors, which we have yet to deter- 

 mine. I doubt not that much light will yet be thrown upon them 

 through patient research. 



This first Table shows that the Longmynd and Harlech rocks are 

 known at the present time to possess 18 genera and 33 species — 

 the commencement of life, so far as we know. The Crustacea are 

 the most abundant class ; 7 genera and 14 species occur : these 

 earliest rocks of St. David's yield Agnostus cambrensis, Hicks, 

 Conocoryphe bufo, Hicks, C. Lyellii, Hicks, C. solvensis, Hicks, 

 Microdiscus sculptus, Hicks, Paradoocides aurora, Salt., P. Hicksii, 

 Salt., P. Harhnessii, Hicks, P. solvensis, Hicks, MS., Plutonia Sedg- 

 ivickii, Hicks, and the Longmynd form Palceopyge Bamsayii, Salt. ; 

 the Ostracoda are Leperditia ferruginea, L. cambrensis, Hicks, and 

 L. primazva. 4 of the above species pass to the Menevian— Agnostus 

 cambrensis, Conocoryphe bufo, Paradoocides aurora, and P. Hicksii. 

 Out of the 6 species of Brachiopoda, 4 also pass to the Menevian — 



