GRIFFITHIDES. 41 



margin 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 Limestone of Northumberland, and 

 a sixth specimen, in the same collection, from the Upper Carboniferous Shale of 

 Ashford, Derbyshire. 



This species in general form agrees most nearly with G. longispinns, Portl. (see 

 ante, p. 36, PI. VII, figs. 5 a, b, c, and 6), but G. glaber, as its name implies, is 

 smooth or nearly so, whereas G. longispinns is coarsely tuberculated both on the 

 head and body segments, the tail alone being smooth. 



In G. glaber there is a trace of minute serration seen on a pygidium from 

 Ashford, Derbyshire, not discernible on the other specimens, but I consider that 

 they all belong to one and the same species. 



Formation. — Carboniferous Limestone. 



Localities. — Castle-Mumbles, Glamorganshire ; Northumberland ; and Ashford, 

 Derbyshire. 



All the above specimens are preserved in the Museum of Practical Geology, 

 Jermyn Street. 



19. Griffithides ? Careingtonensis, Eth., MS. PI. IX, figs. 6 a and b. 



This species, named by Mr. Etheridge, F.R.S., in manuscript, is represented 

 by two pygidia in the collection of the Museum of Practical Geology, Jermyn 

 Street, and one in British Museum series. 



Head-shield and thorax unknown. Abdomen or Pygidium. — The largest 

 specimen (which is preserved in the British Museum) measures 17 mm. in breadth 

 and 15 mm. in length; the axis is 7 mm. broad at its proximal end, diminishing 

 to 3^ mm. at the distal extremity. It terminates at a distance of 3 mm. from the 

 posterior border, which is smooth, and continues so around the semicircular 

 margin of the pygidium. Twelve coalesced somites are indicated by as many 

 broad and flattened rings in the axis, which have a faint vertical line crossing 

 them on each side of the axis and parallel to the axal furrows. The pleurae, 

 nine in number, terminate abruptly about 3 mm. from the margin, and are each 

 divided by a median groove. 



The other and smaller specimens are fig. 6 a, measuring 10 mm. wide by 

 7 mm. long, and fig. 6 b 11 mm. wide by 8 mm. long. 



This species agrees most nearly with G. obsoletus, but the latter has no distinct- 

 margin to the pygidium, and has only ten axal rings. 



