NEOLENUS. 
31 
Fig. 8. — Ncolenus serratus (Rominger). A restoration of the ventral 
surface, with the endopodites omitted from one side, to permit a better 
exposition of the exopodites. The position and number of the appendages 
about the mouth are in considerable doubt. Restored by Doctor Elvira 
Wood under the supervision of the writer. About one-half larger than the 
average specimen. 
Nathorstia transitans Walcott. 
Illustrated : Walcott, Smithson. Misc. Coll., vol. 57, 1912, pi. 28, fig. 2. 
The badly preserved specimen on which this genus and species was based is undoubt- 
edly a trilobite, but for some reason it does not find a place in Walcott's recent article 
on "Appendages" (1918). The preservation is different from that of the associated trilo- 
bites, being merely a shadowy impression, indicating a very soft test. The general outline 
