CRUSTACEA Asaphus emoryl 
Hall, 1857. 
No original diagnosis 
OBSERVATIONS 
There is no original description nor is the locality of the specimen where found given. 
The species is based on a single specimen, 9824, in the U. S. National Museum. In the 
work cited the specimen is figured on plate XX, and the description to this plate, on p. 174, 
states nothing more than « Fig. 5. — Asaphus emoryi ». 
The only known specimen preserves the entire trilobite. The head is bent back and is so 
badly crushed that a photograph of it would not illustrate its true characters. Total length 
of animal (head restored) about 66mm; width across the middle of the thorax about 4omm, 
Surface smooth. 
Asaphus Emoryi belongs to the genus Zsofelus and is most closely related to I. Susæ 
Whitfield (1882. — Whitfeld, Geol. Surv. Wisconsin, t. IV, p. DA IA ENENITE TR AC, 
fig. 8. — 1897. — Clarke, Geol. Surv. Minnesota, t. Il, part. Il, p. 708, text fig. 10, 11). The 
former is distinguished from the latter by the greater proportionate length, the outlines of 
the cephalon and pygidium are more arched, and the latter also has the rachis more strongly 
defined. 
This type of Zsotelus is known only in the Richmond formation of America or in the 
uppermost Lower Silurian. On the back of the holotype is a fragment of Rhynchotrema capax 
a guiding fossil for the Richmond formation. That this horizon occurs in the region of 
El Paso, Texas, is known by collections recently made at this locality by the U. S. Geolo- 
gical Survey though no specimen of /. Emoryi has been found there. 
1903. Ch. D. Walcoit. 
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