NO. 5 CAMBRIAN TRILOBITES 359 



Asiatic species. — The eastern Asiatic species of the genus all differ 

 from the Swedish and American species in their associated pygidia. 

 The latter have fewer segments in the axial lobe and more distinct 

 prolongation of the axial segments on the pleural lobes. The pygidia 

 are more like those of the species of Bathyuriscus with small py- 

 gidium such as B. (Poliella) powersi (pi. 46, fig. i) and B. (Poliella) 

 primus (pi. 46, fig. 6). If we had entire specimens of the dorsal 

 shield of D. (f) deois and other Asiatic species, so that there could be 

 no doubt that the associated pygidia belong with the cranidia, I 

 should not hesitate to make a new subgenus of Dolichonietopus to 

 include them. Dolicho met opus {?) deois (pi. 54, figs, i, la-h) is the 

 most abundant of the Chinese species in the form of dismembered 

 parts of the dorsal shield, and it is found in both shale and limestone. 



There also appears to be a subgenus of Dolichometopiis indicated 

 hy D. f bessus {^\. 51, fig. 3). It is characterized by a smaller pygidium 

 very much as in the group of species of the subgenus Poliella (p. 349) 

 which are those species of Bathyuriscus characterized by a small 

 pygidium. Further collecting and study may result in separating 

 D. ? bessus and several of the species illustrated on plate 54 as sub- 

 generic species of Dolichonietopus. 



Species of Dolichometopiis.— -The species now referred to Dolicho- 

 metopus are : 



Dolicho me to pus acadicus Matthew (pi. 53, fig. i), Middle Cambrian. 

 Dolichonietopus (f) alceste Walcott (pi. 54, fig. 3), Middle Cambrian. 

 Dolichonietopus baton Walcott (pi. 51, fig. 2), Middle Cambrian. 

 Dolichonietopus ? bessus Walcott (pi. 51, fig. 3), Middle Cambrian. 

 Dolichonietopus bion Walcott (pi. 52, fig. 2), Middle Cambrian. 

 Dolichonietopus boccar Walcott (pi. 52, fig. i), Middle Cambrian. 

 Dolichonietopus (?) deois Walcott (pi. 54, fig. i), Middle Cambrian. 

 Dolichometopus {?) derceto Walcott (pi. 54, fig. 4), Middle Cambrian. 

 Dolichonietopus {?) dirce Walcott (pi. 54, fig. 5), Middle Cambrian. 

 Dolichonietopus ? expansus (Walcott) (pi. 53, fig. 5), Middle Cambrian. 

 Dolichonietopus productus (Hall and Whitfield) (pi. 53, fig. 2), Middle 



Cambrian. 

 Dolichometopus suecicus Angelin (pi. 50, figs. 3, 4), Middle Cambrian. 

 Dolichonietopus tontoensis Walcott (pi. 51, fig. i), Middle Cambrian. 



Generic reference of species heretofore placed under Dolichometo- 

 pus and now referred as follows: 



Dolichometopus (?) conve.vus Billings = Bolboccphalus Whitfield ? 

 Dolichometopus (?) gibberulus Billings =: Platycolpus Raymond ? 

 Dolichometopus hyrie 'Walcott = Atwmocare. 

 Dolichometopus occidentalis Matthew ^ Bathyuriscus. 

 Dolichometopus (?) rarus Billings ^= Bolboccphalus Whitfield ? 

 Dolichometopus tatei Woodward ^= Redlichia Cossmann. 



