400 Prof. F. M'Coy on the Classification of 



and duplicate lateral furrows; thoracic segments ten, pleural 

 grooves slightly oblique, facets large. 



Subgen. 1. Forbesia (M'Coy) = JEonia, Burm. Cephalic 

 angles produced ; glabella with three pair of segmental 

 furrows ; ends of neck-segment forming large tubercles. 



Subgen. 2. Proetus (Stein.). Cephalic angles not produced ; 

 no segmental furrows to glabella. 



7. Phillipsia (Portk., extended). General character of Forbesia, 

 but only nine thoracic segments. (Carboniferous.) 



Subgen. 1. Phillipsia (Portk.). Base of glabella wide, sides 



with three segmental furrows. 

 Subgen. 2. Griffithides (Portk.). Base of glabella contracted, 



sides without segmental furrows. 



2nd Subfam. Paradoxus. 



Head large ; pygidium diminutive ; thorax long ; pleurse flat, not 

 bent down at the end, terminating in ldng spines ; pleural 

 grooves straight ; no facets. 



An easily recognized group of long-bodied, flat Trilobites with 

 large heads, the angles of which and the ends of the pleurse are 

 produced backwards into sharp spines. None of these can roll 

 into a ball. 



1. Paradoxides (not British). 



Subgen. 1. Olenus (Dal.). Fourteen thoracic segments; 

 pygidium small, with entire margin. 



2. Ceraurus* (Green, emended by Hall). Glabella cylindrical, 

 reaching the front margin, with three pair of segmental fur- 

 rows ; facial suture cutting the outer margin considerably in 

 front of the angles ; eleven thoracic segments ; pleurse each 

 with a short oblique pleural groove dividing its tumid origin, 

 ends flat, falcate ; pygidium moderate, the margin with six or 

 eight thick spines ; cephalic angles prolonged. 



3. Cryph^eus (Green) = t Eccoptochile (Hawle and Corda). Head 

 as in Ceraurus ; twelve thoracic segments ; pleurse wide, di- 

 vided by a long mesial pleural furrow not reaching the margin ; 

 ends thickened and each extended in a slender spine ; pygi- 

 dium of three thin flat lobes on each side. 



4. Sph^erexochus (Beyrich). Glabella hemispherical ; posterior 

 pair of segmental furrows very large, circular, two anterior 

 pair rudimentary or absent ; lateral angles rounded, divided 



* Chirurus (Beyrich) is I think certainly a synonym of this genus; the 

 recently published figures by Hall (Palaeontology of New York), of Green's 

 original specimen of Ceraurus, showing all the characters of the Bohemian 

 genus. 



