Frof. C. Lapicorth — On Olenellus Callami. 533 



The generic position of the two characteristic forms of the Lower 

 and Upper Divisions of the Coraley Series being thus settled, the 

 descriptions of the less important associated forms may conveniently 

 be deferred to a more favourable occasion. 



We possess in the foregoing facts sufficient palaeontological 

 evidence to establish the Lower Cambrian age of that part of the 

 Comley series which contains the genus Olenellus ; and we have 

 now obtained stratigraphical and palaeontological proof that it is 

 succeeded at once by the so-called Middle Cambrian or Paradoxiclian. 

 Further, as Dr. Callaway^ originally pointed out some years ago, 

 the Hollybush (or Comley Sandstone) series is followed in turn 

 by the Shineton Shales, which contain locally a fauna of highest 

 Cambrian age. In these Central Shropshire rocks, therefore, the 

 Comley and Shineton Groups, which constitute an integral part in 

 this district of Murchison's original Loioer Silurian, and have a 

 collective thickness of perhaps less than 3000 feet, we have apparently 

 a condensed epitome of the entire Cambrian system as at present 

 generally defined. 



Here, as elsewhere, we find the Cambrian divisible into three 

 sections — an Upper Cambrian above, marked by the presence 

 of the genus Olenus (Olenidian) ; a Middle Cambrian group with 

 Paradoxides (Menevian or Paradoxidian) ; and finally a Lowt^r 

 Cambrian (Olenellus zone) or basal group (possibly of somewhat 

 different systematic importance), distinguished by the presence 

 of Olenellus. No one has yet, so far as I know, suggested any 

 general title for the basal division of the Cambrian. Recollecting, 

 however, that the very first discovered species of the genus Olenellus 

 was named and figured^ by the American geologist, Dr. Emmons, as 

 early as 1846 from the rocks of his Taconic or Taconian system ; and 

 was claimed by him as early as 1853 ^ as coming from strata older 

 than any of the fossil-bearing Silurian (including the Primordial 

 zone) then discovered ; while even at the present day the genus holds 

 its own as marking a distinct and identifiable life-zone in the strata 

 of Emmons' typical Taconic area ; it would be very convenient if 

 geologists and palasontologists generally would agree in calling it 

 the Taconian. 



In my short paper already referred to, " On the Discovery of the 

 Olenellus Zone in Britain," I drew a few provisional inferences, 

 novel at that time, but thrown out then as "constituting a pro- 

 visional working hypothesis, of service mainly as a guide and 



F«r. Hnrlani (Green) and Par. Davidis (Salter). Length 8 to 9 inches, breadth 5|-. 

 Head semi-circular, with pointed genal spines from two to three inches in length. 

 Glabella prominent, clavate, more than half its length being occupied by the broadly- 

 rounded and smooth frontal lobe. Eypostoma of the type of that of Par. Bolmnicus 

 (Boeck). Pleurce (no ?) falcate, and sharply pointed. Pygidium a raised disc with 

 central tubercle ; embraced laterally by long, sabre-like, distally-diverging spines. 

 Localities. Neves Castle (Lapw., 1889) and Comley (Groom, 1890). Named after 

 T. Theo. Groom, Esq., B.Sc, who first collected fragments sufficient for description. 



' C. Callaway, "Upper Cambrian Kocks in South Shropshire," Q.J.G.S. 1877, 

 p. 652, etc. 



"^ As EUiptocephala asaphoides, Emmons, Taconic System, 1846, p. 213, figs. 1, 2, 3. 



3 Emmons' American Geology, 1855, pt. ii. pp. 6 and 7, etc, ■ 



