126 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 75 



expanded and the associated pygidium is wider and less triangular. 

 The axis is also outlined farther back. 



Formation and locality. — Ozarkian: (67q) Mons formation. 

 Douglas Lake Canyon Valley, Sawback Range, Alberta, Canada. 



XENOSTEGIUM EUCLIDES, new species 

 Plate 24, figs. 13, 14 



Observations. — The pygidium of X. euclides is readily distinguish- 

 able from X. albert ensis which occurs in the same beds, being less 

 convex and robust. The axis extends nearer to the posterior margin 

 and both axial and pleural furrows are traceable on the anterior 

 portion. 



X. euclides differs from the genotype in its more sharply triangular 

 outline, and longer, more slender median axis. 



The associated hypostoma assigned to Xenostegiwii must be re- 

 garded as tentative, as it indicates the kind of hypostoma it may 

 have had. 



. Formation and locality. — Ozarkian: (66v) Mons formation. Upper 

 Johnson Creek Canyon, Sawback Range, Alberta, Canada. 



XENOSTEGIUM ? EUDOCIA, new species 



Plate 24, fig. 12 



Observations. — The cranidium on which this species is founded 

 is unusual. It is referred tentatively to Xenostegium, as the one 

 fragmentary specimen will not permit of an accurate determination. 

 It departs from the genotype of Xenostegium in characters that might 

 give it a different generic reference if better material were available. 

 It may possibly be congeneric with X. ? sulcatum (fig. 9, pi. 24) from 

 the same locality. The cranidium is long and narrow. A shallow 

 dorsal furrow outlines the slightly expanded glabella ; the frontal limb 

 is concave as in X. goniocercum but it is shaped differently. Fixed 

 cheeks very narrow. The greatest peculiarities in this strong cra- 

 nidium are the depression occupying the position of the posterior 

 pair of glabellar furrows and the occipital furrow. Between them 

 lies a very pronounced swelling, and on the ridge between them is a 

 median tubercle. 



X. eudocia departs from typical forms of Xenostegium in the less 

 expanded glabella, the narrowness of the cranidium and the peculiar 

 furrow pits. 



