152 TRILOBITES OF GTRVAN. 



points of difference, as in the case of the Keisley specimens; ' but this remains to 

 be proved. 



Collection*. — Mrs. Gray (f. M.) ; Edinburgh Museum. 



Horizons and Localities. — Stinchar Limestone Group (Llandeilo) : Craighead; 

 Minuntion ; Auchensoul. Balclatchie Group (Llandeilo) : Balclatchie (Con- 

 glomerate) ; Dow Hill? 



Genus STAUROCEPHALUS, Barrande. 

 1. Staurocephalus globiceps (Portlock), 1843. 



1843. Ce/aurus globiceps, Portlock, Geol. Rep. Londond., p. 257, pi. i, fig. 7. 



1854. Staurocephalus globiceps, Morris, Cat. Brit. Foss., ed. 2, p. 115. 



18G5. Staurocephalus globiceps, Salter, Mem. Geol. Surv., dec. xi, pi. v, fig. 6. 



1865. Staurocephalus globiceps, Salter, Moil. Brit. Trilob., p. 85, pi. vii, fig. 21 (? woodcut, fig. 18, 

 p. 86). 



1877. Staurocephalus globiceps, Woodward, Cat. Brit. Foss. Crust., p. 59. 



1878. Staurocephalus globiceps, Nicholson & Etheridge, Mon. Silur. Foss. Girvan, fasc. i, p. 117. 

 1899. Staurocephahis globiceps (e. p.), Mem. Geol. Surv., Silur. Rocks Brit., vol. i, Scotland, pp. 513, 



674, 689. 



Remarks. — The specimen attributed to this species by Salter and figured by 

 him (' Mon. Brit. Trilob.,' p. 86, fig. 18) is in the Museum of Practical Geology, 

 and came from Ardmillan. Nicholson and Etheridge (M, fasc. i, 1878, p. 117), 

 remark that this figure " does more than justice to the specimen," and such is 

 indeed very much the case. I have grave doubts if it can be attributed to this 

 species. It is in a poor state of preservation, and the glabella is completely 

 destroyed and the pygidium is not preserved ; but there are suspicious indications 

 of lateral spines on the margin of the head-shield, and the pleurae are precisely 

 similar to those of Sphsero. thomsoni, with which species it should most probably be 

 placed. The genal spines appear, however, to be rather stouter. 



On the other hand, there are fortunately now two good and nearly complete, 

 though small, specimens of St. (jlobiceps, collected recently by Mrs. Gray from the 

 Starfish Bed, the identification of which cannot be disputed. They show all the 

 typical characters of the head and thorax as described and figured by Salter, 

 and the pygidium, so far as it is preserved, is likewise identical with the type. 



Collections. — Mrs. Gray ; Museum of Practical Geology. 



Horizons and Localities. — Drummuck Group (U. Bala) : Starfish Bed, Thraive 

 Glen. ? Balclatchie Group (Llandeilo): Ardmillan. 



1 Reed, 'Quart. Journ. Geol. Soc.,' vol. Hi (1896), p. 423. 



