314 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 53 



terminal spine of Olcnelhis proper, suggests that in the latter sub- 

 genus posterior segments of a purely membranous character may have 

 existed, devoid of hard parts." 



Dr. Charles E. Beecher [1897, P- 191]' i" his memoir on "Out- 

 line of the Natural Classification of the Trilobites," says of the fam- 

 ily Paradoxiiicr, " Most of the genera are distinguished by their long, 

 narrow eyes .... but more especially by the rudimentary character 

 of the pygidium. In OlcncUiis the pygidium is a long telson-like 

 spine." 



Geographic distribution. — OloicUns, as restricted, is found in the 

 sediments of the Appalachian sea as 0. thoinpsoni ( Hall) on the east- 

 ern side of the great pre-Cambrian Algonkian North American conti- 

 nental area from the Straits of Belle Isle to central Alabama. On 

 the western side it occurs as 0. canadensis Walcott and 0. gilberti 

 Meek as far north in British Columbia as Kicking Horse Pass in 

 the Rocky Mountains ; in Utah as O. gilberti Meek in the Wasatch 

 Mountains ; in the Eureka mining district of Nevada as O. fremonti 

 Walcott; in the Pioche mining district and vicinity as 0. fremonti 

 Walcott ; and in southwestern Nevada and southeastern California as 

 O. fremonti, 0. argentiis, and 0. f claytoni. 



At all the American localities Olenellus (restricted) occurs in the 

 upper parts of the Lower Cambrian terrane. 



On the eastern side of the Atlantic Basin O. thompsoni is repre- 

 sented by the closely allied 0. lapzvorthi Peach and Horn [1892, p. 

 236] of northwest Scotland. This locality has also given 0. reti- 

 culatus Peach [1894, p. 665], and 0. gigas Peach [1894, p. 666]. 



As far as known, Olenellus does not occur on the Asiatic conti- 

 nent. If found at all, it will probably be in sediments deposited on 

 the outer margins of that continental area in early Cambrian time 

 prior to the transgression of the Middle Cambrian sea over large 

 areas of what is now Siberia, Manchuria, central and eastern China, 

 and northern India. 



OLENELLUS ? ARGENTUS, new species 



Plate 40, Figs. 12-16 



Holniia rozvei Walcott (in part), 1908, Smithsonian Misc. Coll.. Vol. 53, 

 No. 5, p. 189 (3 of section only). (The specimens listed under this 

 name from 3 of the Barrel Spring section are referred in tliis paper to 

 Olenellus argentiis and Olenellus gilberti.) 



Of this species only the cephalon is known. The globose anterior 

 lobe of the glabella, very strong marginal border, small palpebral 



