NO. 5 CAMBRIAN TRILOBITES RESSER 21 



Clavaspidella anax (Walcott) 



Bathyuriscns anax Walcott (part), Smithsonian Misc. Coll., vol. 64, no. 5, 

 P- 335- pl- 48, figs. I, la, ic, id (not ib), 1916. 



A mere glance at the illustrations shows that the forms from Cotton- 

 wood Canyon referred to this species belong to Glossoplcura. 



Middle Cambrian, Ophir ; (loc. 55e) Wasatch Range, north of 

 Brigham City, Utah. 



Lcctotvpc. — U.S.N.M. no. 62637; paratypes, nos. 62638-40. 



Clavaspidella sylla (Walcott) 



Bathyuriscns (Policlla) sylla Walcott, Smithsonian Misc. Coll., vol. 64, no. 5, 

 p. 354, pi. 65, figs. 2, 2a, 1916. 



This species approaches the extreme limits of the genus, but until 

 more forms become available it seems inexpedient to make another 

 genus. 



Middle Cambrian, Marjum ; (loc. llo) 4 miles southeast of Ante- 

 lope Springs, House Range, Utah. 



Cotypes.—U.S.'NM. nos. 62837-8. 



COOSIA Walcott, 191 1 



Coosia calanus (Walcott) 



Asaphiscus calanus Walcott, Smithsonian Misc. Coll., vol. 64, no. 5, p. 384, 

 pi. 61, figs. 8, 8a, 1916. 



Upper Cambrian, Nolichucky ; (loc. 47h) Wolf Creek, Bland 

 County, Virginia. 



Cotypcs. — U.S.N.M. nos. 62789-90. 



DEIRACEPHALUS, n. gen. 



Several Upper Cambrian forms previously referred to Acrocephali- 

 tcs may be descendants of Middle Cambrian forms but are generi- 

 cally distinct. 



Diag)iosis. — Cranidium quadrate in general outline. Sutures diverg- 

 ing slightly anteriorly. Glabella tapering, rather conical, somewhat 

 over half as long as the cranidium ; no glabellar furrows visible on 

 available specimens. Brim wide with a narrow rim of even width ; 

 preglabellar area crossed by a vertical median ridge, beginning at the 

 dorsal furrow and widening out to join the brim. Eye lines strong ; 

 palpebral lobes small, situated a little behind the middle of the cra- 

 nidium. Occipital furrow separating the neck ring, which bears a spine. 

 A beautiful compound eye has been preserved on a free cheek. Sur- 

 face richly ornamented by pustules, or pustules and lines. 



