THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE V. VOL. VI. 

 No. v. — MAY, 1909. 



I. — Notes ox the Trilobite Fatjx.v of Devon and Cornwall.^ 



By Ivor Thomas, Ph.D., B.Sc, F.G.S. 



(PLATE VII.) 



rriHE material iipou which the following descriptions are based was 

 JL obtained chiefly by Mr. Ussher, who collected the AVhiteway and 

 Hestow Farm specimens. The Daymer Bay form was collected by 

 Mr. John Pringle. For the new species of Proetus I am indebted 

 to Mr. Claude H. Peter, Town Clerk, Lannceston, who, through 

 Mr. Clement Reid, kindly lent it for description. It is evident from 

 the examination of this limited quantity of material that the British 

 Devonian fauna is not yet fully known. We may expect the discovery 

 of many species hitherto unrecorded in this country, which will be of 

 interest from the possible comparative relationship with the fauna of 

 foreign deposits. The accompanying illustrations were drawn by my 

 colleague, Mr. H. H. Thomas, to whom I tender my best thanks. 



PHACOPID^. 



Phacops (Trimerocephalus) anophthalmus, Freeh. PI. VII, Fig. \. 



1866. Phacops cryptophtludmus, F. Roemer : Zeitsclir. d. d. geol. Ges., Bd. xviii, 



p. 67-1, pi. xiii, figs. 6, 7. 

 1871. ,, ,, E. Tietze : Pakcontographica, Bd. xix, p. 126, 



pi. xvi, fig. 1. 

 1876. ,, ,, P.Eoemer: LethteaPalajozoica, i, pi. xxxv, fig. 18. 



189-1. ,, {Trimerocephalus) anophthalmus, Freeh: Die Karnischen Alpen, 



p. 270. 

 1896. Tfimerocephalus typhlops, Giirich : Verhdl. d. Euss.-k. Min. Geol. zu 



St. Petersbui-g, Bd. xxxii, p. 359, pi. xv, fig. 7. 

 1900. Phacops [Trimerocephalus) anophthalmus, Drevermanu : Jahrb. d. k. preuss. 



geol. Landesanst., Bd. xxi, p. 117. 



Description. — The cephalon is broadly semicircular, the length being 

 about 8 mm. and the greatest breadth about 14 mm. The posterior 

 limit is almost straight. The marginal border is fairly broad, and 

 extends from the rounded genal extremities to the frontal margin of 

 the glabella, and is continued anteriorly as a narrower and less distinct 

 rim to the overhanging frontal lobe. 



1 By permission of the Director of the Geological Survey. 



DECADE V. VOL. VI. — XO. V. 13 



