100 TRILOBITES OF GIRVAN. 



1885. Lichas grayi, Lindstrom, Forteckn. Gotl. Silur. Crust. (Ofv. k. vet. Akad. Forhandl., No. 6), 



p. 60. 

 1902. Lichas (? Platylichas) grayi, Eeetl, Quart. Journ. Geol. Soc, vol. lviii, p. 72. 



Yar. nov. scoticus. Plate XIV, figs. 5- — 10. 



? 1854. Lichas rotwndifrons, Augeliu, Pal. Scand., p. 70, pi. xxxvi, figs. 7, 7a, 7b. 

 1873. Lichas bulbiceps?, Salter, Cat. Camb. Silur. Foss. Woodw. Mus., p. 77. 

 1878. Lichas grayiif, Nicholson and Etheridge, Mon. Silur. Foss. Girvan, fasc. i, p. 134, pi. ix, 



figs. 11, 12. 

 1878. Lichas barrandei ?, Nicholson and Etheridge, ibid., p. 132, pi. ix, fig. 8. 



Remarks. — In addition to the single head-shield from Mnlloch Hill figured by 

 Nicholson and Etheridge (op. cit.) as doubtfully belonging to L. grayi, Fletcher, 

 there are several others from the same locality, and one from Craigens, which 

 enable us to describe the characters of this form more in detail. A large fragment 

 of a glabella from Camregan Wood, also in Mrs. Gray's collection, probably belongs 

 to it ; and the specimen in the Woodwardian [Sedgwick] Museum from Mulloch, 

 called by Salter (op. cit.) " L. bulbiceps, Phillips?" appears to be a crushed head- 

 shield of the same species. 



The Mulloch Hill and Craigens specimens differ from the typical L. grayi of 

 the English Wenlock by (1) the strong deflection of the anterior portion of the 

 head-shield ; (2) the shorter central lobe of the glabella, and its more rapid and 

 greater expansion in front, so as to overlap the bicomposite lobes to a greater 

 extent; (3) the broader and more oval shape of the bicomposite lobes, their relative 

 shortness and stronger convergence posteriorly ; (4) the narrowness of the neck of 

 the central lobe ; (5) the stronger convergence posteriorly of the axial furrows ; 

 and (6) the generally greater convexity of the head-shield. 



In other respects this Scottish form has the closest resemblance to the English 

 Wenlock species, and it does not seem possible to regard it as more than a distinct 

 variety which may be appropriately termed scoticus. L. rohmdifrons, Angelin, 1 

 from the equivalent of the Wenlock Shales of Scotland, may prove to be identical 

 with this Girvan form, as it seems to differ from the typical L. grayi in much the 

 same way. Lindstrom 2 considered L. rotundifrons, Ang., to be identical with 

 //. grayi, Fletcher, but this is very doubtful. 



In addition to the above head-shields there are certain pygidia, also from Mulloch 

 Hill and Craigens, which most probably ought to be referred to the same variety 

 on the strength of their resemblance to L. Tnargaritifer, Nieszk., which is the type 3 

 of the group of Lichas to which L. grayi may now be referred with certainty from 



'Angelin, 'Pal. Scand.,' p. 70, pi. xxxvi, figs. 7. 7a, 7b. 



2 Lindstrom, ' Forteckn. Gotl. Silur. Crust.' (Ofv. k. vet. Akad. Forhandl., No. 6), 1885, p. 60. 



3 Reed, 'Quart. Journ. Geol. Soc.,' vol. lviii (1902), p. 72, figs. 3 a, b. 



