44 TRILOBITES OF GIRVAN. 



than its length, cutting off anterior narrow band ; extremities of pleurge short, free, 

 slightly bent outwards, and ending at same level jjosteriorly ; one or two tubercles 

 present along each pleura. 

 Dimensions. — 



Length of head-shield . . .9-0 mm. 



AVidthof „ „ . . . 20-0 „ 



Width of glabella at base . . .50,, 



Length of thorax (about) . . . 17*0 „ 



„ of pygidium .... G'O ,, 

 Width of „ . . . .7-5 „ 



BemarJiS. — The above diagnosis is based on one complete specimen with a 

 perfect head-shield, thorax (save for the ends of the pleurge) and pygidium. The 

 external impression of the same specimen is also preserved, and thus the species 

 is capable of precise definition. It is clearly distinct from G. as])eva, Linnarsson, 

 with which some fragments of head-shields from Ardmillan and Dow Hill have 

 been previously compared by the author, and it is probable that the pygidium 

 described as Ci/hele sp. h is also referable to this new species. 



The peculiar position of the rostral suture and shield in the species above 

 described is met with also in C. affinis, Schmidt,^ from the Baltic Ordovician, and 

 in the other characters of the head-shield these species bear a considerable mutual 

 resemblance. C. wortld, Eichwald^ and G. hutorgx, Schmidt,^ apart from this one 

 feature, are allied, but our Girvan form is undoubtedly distinct from them. It is 

 named michelli, after a former Woodwardian Professor. 



Horizon and Localities. — Balclatchie Group : Ardmillan and Doav Hill. 



Genus DINDYMENE, Corda. 

 Dindymene cordai, Etheridge, junr., and Nicholson. Plate VII, figs. 8, 9. 



1906. Bindymene cordai, Keed, op. cit., pt. iii, p. 182, pi. xvii, figs. 9—11. 



In several specimens of the head-shield of this species occurring in the Starfish 

 Bed, there can be observed the interesting and previously undescribed feature of 

 the presence of an apparent marginal fringe of small spines. These " spines " 

 project forwards horizontally in the general plane of the head-shield, and are slender 

 and curved sigmoidally outwards ; all seem to be of equal or subequal size and to 

 project a little further than the border is wide. They seem to be about 8 or 9 in 



> Schmidt, ' Eev. Ostbalt. Silur. Trilob.,' pt. i, p. 216, pi. xiii, figs. 18, 19. 



2 Schmidt, ibid., p. 214, pi. xiii, figs. 14—17. 



3 Schmidt, ibid., p. 217, pi. xv, figs. 11—14; pi. xvi, figs. 39a, h. 



