Carboniferous Limestone Trilobites. 485 



Langside, Beith, Ayrshire, N.B., are two fragments of heads of a 

 small species of Trilobite of the genus Grijithides, which, as the 

 discoverer observes, appear to differ from any which have hitherto 

 come under notice from the Carboniferous Limestone. The head is 

 nearly twice as broad as it is long, the free-cheek terminating 

 laterally in a short spine ; the eye, which is very smooth, is rounder 

 and more tumid than in other species, and the facets, which are 

 readily discernible with a Browning's platyscopic lens, are very 

 minute, and do not break the smooth hyaline surface of the com- 

 pound eye. 



The glabella is nearly smooth in front, and overhangs the anterior 

 border of the head-shield, the posterior portion of the glabella and 

 the neck-lobe are irregularly tuberculated. The free-cheek is also 

 tuberculated, and has about eight tubercles on each cheek, placed in 

 a semicircle around the compound eyes. The margin of the shield is 

 raised and striated, and has a rather deep and smooth furrow between 

 the raised border and the inner portion of the free-cheek. 



In the style of its ornamentation this form agrees most nearly with 

 G. longispinus, Portl.,^ but the head is shorter and broader, and the 

 spines are only one-half the length. 



Formation. — From the Lower Carboniferous Limestone. 



Locality. — Langside, Beith, Ayrshire. 



From the collection of Mr. Robert Craig, of Langside, Beith, 

 Ayrshire, N.B. 



Griffithides glaber, H. Woodw., 1884. Plate XVL Fig. 5. 



Griffithides glaber, H. "Woodw., Pal. Soc. Mon. Carb. Trilob. part ii. 1884, p. 40, 

 plate ix. figs. 4« and 46. 



The original specimen is preserved in a dark crystalline rock from 

 the Carboniferous Limestone, Castle-Mumbles, Glamorganshire, The 

 extreme length of the more complete specimen is 36 mm., and its 

 greatest breadth 13 mm. Length of glabella, including neck-lobe, 

 12 mm. ; length, of pygidium 13 mm. The head is much mutilated, 

 but sufficient of it remains to show that the glabella was smooth, 

 rather tumid, longer than wide, with a basal-lobe on each side near 

 the neck ; neck-lobe moderately broad, and marked with one central 

 tubercle ; the eyes are not preserved ; border of free-cheek termi- 

 nating in a short lateral spine on each side, and striated below. Free 

 thoracic somites nine in number ; extremities of pleui'^ smooth and 

 truncated ; axis rather wider than lateral portion of somite ; coalesced 

 abdominal somites about nine in number ; axis nearly smooth, with 

 a slightly serrated posterior edge to each body-ring, mai'gin smooth, 

 rather broad ; the pygidium is somewhat narrower and more 

 elongated than in the other Carboniferous species. 



Five specimens of pygidia referable to this species are preserved 

 in the Museum of Practical Geology, from the Carboniferous Lime- 

 stone of Northumberland ; there is also a sixth specimen in the 

 same collection, from the Upper Carboniferous Shale of Ashford, 

 Derbyshire. 



1 See Geol. Mag. 1883, p. 485, PI. XII. Fig. 5. 



