DESCRIPTION OF GENERA AND SPECIES. 1 07 



Genus DORYPYGE Dames. 



Dorypyge DAMES, 1883, China, Richthofen, vol. iv, p. 23. (Description and discussion of the genus.) 

 Dorypyge ZITTEL, 1885, Handbuch der Pal., vol. n, Munich, p. 596. (Gives brief outline of genus.) 

 Dorypyge WALCOTT, 1886, Bull. U. S. Geol. Survey No. 30, p. 221. (Considers that Dorypyge may be 



synonymous with Olenoides.) 

 Dorypyge WALCOTT, 1889, Proc. U. S. Nat. Mus., vol. xi, p. 443. (Expresses opinion that Dorypyge 



and Olenoides are congeneric.) 

 Dorypyge MATTHEW, 1897, Trans. Roy. Soc. Canada, 2d ser., vol. in, sec. 4, p. 186. (Discusses genus 



and its relations to Olenoides.) 

 Dorypyge VON TOLL, 1899, Mem. de 1'Acad. Imp.des Sciences de St. Ptersbourg,8thser., vol.vm.No. 



i. P- 35- (Discusses reference of species to Dorypyge and Olenoides.) 

 Dorypyge GRONWALL, 1902, Danmarks geol. Unders., 2d ser., No. 13, p. 126. (Discusses the genus at 



length and accepts Matthew's interpretation of it.) 



Original description. "Cephalic shield arched, with narrow, upturned frontal 

 border. Facial sutures somewhat converging in front of the eyes, but widely sepa- 

 rated at the anterior rim, and diverging behind the eyes to ward the posterior border. 

 Glabella high-arched, with three pairs of horizontal furrows but slightly developed. 

 The neck-ring is widened cushion-like behind and runs out into a spine which is 

 directed obliquely upward. 



"Pygidium large ; axis high-arched and sharply set off all around ; axis and lateral 

 parts divided into few but clearly defined segments; margin running out into a 

 number of spines equal to the number of segments. Surface of cephalic and tail 

 shields ornamented with fine warts." [Dames, 1883, p. 23.] 



Doctor Dames compared the genus with Peltura and Parabolina on account 

 of the course of the facial sutures and the presence of a spinose pygidium, and on 

 this account placed the genus in the Olenid family. He states under the descrip- 

 tion of the type species, D. richthofeni Dames, that large numbers of the cephala 

 and pygidia occurred in the collection, but none of the thoracic segments. In the 

 material collected by Mr. Blackwelder fragments of the thoracic segments occur, 

 and these show that the pleural groove is straight [see plate 8, fig. id], as in Olenoides, 

 and not oblique, as in the Olenidas and Paradoxidae. 



The differences between Olenoides and Dorypyge are: 



(a) The glabella of Olenoides expands toward the front, while that of Dorypyge 

 contracts in front of the pits in the dorsal furrow. 



(b) The pleural lobes of the pygidium of Olenoides have broad, shallow furrows 

 with sharp, narrow ridges separating them, while those of Dorypyge have narrow 

 furrows with broad, rounded ridges between them. The type of Olenoides, 0. 

 nevadensis, has a finely granulated surface, and the type of Dorypyge a coarsely 

 granulated surface. Species with a nearly smooth surface occur in both genera, 

 e. g., Olenoides curticei Walcott [1890, plate 94, fig. i], Dorypyge richthofeni l&vis 

 Walcott. 



Genotype. Dorypyge richthofeni Dames [1883, p. 24!. 



To the type species there have since been added from Asia: Dorypyge slat- 

 kowskii Schmidt, Dorypyge bispinosa Walcott, and Dorypyge richthofeni lavis Walcott. 



Dorypyge bispinosa Walcott. 



Plate 8, Figure 3. 



Dorvpvge bispinosa WALCOTT, 1905, Proc. U. S. Nat. Mus., vol. xxix, p. 28. (Described and discussed 

 as a new species essentially as below.) 



This species is based on a pygidium having a strong, broad axis, narrow pleural 

 lobes, and two long, strong spines that project obliquely backward from the postero- 



