barton: a new genus of the cheiruridae. 549 



affinities of Cheirurus mitis Salter, with Ch. ornatus Dalman, C. exsul 

 Beyrieh, and C. macropthalmus Kutorga, but especially with the first. 

 He also says that it may be compared with Cheirurus polydorus 

 Billings. Of the specimens figured by Reed the greater number would 

 seem to me to be of the type of the Russian Ceraurus rather than of 

 Ceraurinus. Figures 18 and 20, plate 15, however, resemble very 

 closely C. ornatus Dalman, and C. polydorus Billings. 



Of the actual homogeneity of this genus I have some doubts. 

 Ceraurinus marginatus, C. icarus, C. scofieldi, and possibly C. pompilius, 

 would seem to form one group. Ceraurinus trentonensis and C. poly- 

 dorus each present a slightly different aspect. The Russian form that 

 I have seen resembles Ceraurinus trentonensis rather than the others. 

 The Bohemian form differs slightly in aspect from all the others. 



Key to Species of Ceraurinus. 



A. Glabella expanding slightly forward. 



a . Anterior two pairs of glabellar furrows straight or nearly straight 



ornatus Dalman 



b. Anterior two pairs of glabellar furrows curving 



trentonensis, sp. nov. 



B. Glabella with parallel or faintly convex sides 



a. Glabellar furrows curving 



I. Glabella and cheeks moderately convex 



Surface of the glabella smooth polydorus Billings 



Surface of the glabella shagreened ingricus Schmidt 



Glabella and cheeks not very convex 



Glabella strikingly rectangular (although with rounded 

 corners) comes Barrande 



b. Glabellar furrows straight or nearly straight 



II. Basal lobes not separated from the body of the glabella or 



only faintly separated 

 The three pairs of glabellar furrows perpendicular to the 



dorsal furrows and nearly parallel to each other. 



marginatus, sp. nov. 

 Posterior pair of glabellar furrows inclined slightly backward 



and faintly curving at the inner ends, .ornatus Dalman 

 Posterior pair of glabellar furrows straight and inclined 



strongly backward scofieldi Clarke 



Posterior pair of glabellar furrows not reaching the dorsal 



furrows confluens, sp. nov. 



