NO. 24 PTARMIGANIA STRATA RESSER 45 



of fusion and a greater convexity, in keeping with the greater con- 

 vexity of the cranidium. 



Genotype. — 0. typicalis, n. sp. 



ORYCTOCEPHALITES TYPICALIS, n. sp. 



Plate 3, figs. 1-6 

 The generic description and the illustrations present all the essential 

 characteristics of this species. 

 Locality 54s. 

 Holotype and paratypes.—U .S.N .M. Nos. 98528a-f . 



ORYCTOCEPHALUS Reed, 1898 

 ORYCTOCEPHALUS MALADENSIS, n. sp. 

 Plate 3, figs. 7-9 

 . About 75 cranidia, but part of only one pygidium, have been found 

 in the collections. This species is wholly typical of the genus, as the 

 cranidium has a quadrate outline and a long parallel-sided glabella, 

 with three pairs of furrows clearly indicated. The eye lines are 

 prominent, and the rim is narrow, particularly in front of the gla- 

 bella. The eyes are large and set practically parallel to the dorsal 

 furrow. The fragment of the pygidium shows that segmentation is 

 normally developed and no doubt there are long slender marginal 

 spines. 



O. maladensis is very much like 0. zvalcotti of the Spence shale. It 

 averages smaller. Difference is noticeable in relief which is discounted 

 by compression of the Spence shale. The chief difference is in the 

 brim, where O. maladensis has a wider space between the eye lines 

 and the anterior furrow on the anterior fixigenes, and also has a 

 thickened instead of a flat rim. 



Locality 54s. 



Holotype and paratypes. — U.S.N.M. Nos. 98529^:. . 



TONKINELLA Mansuy, 1916 

 TONKINELLA IDAHOENSIS, n. sp. 



Plate 2, fig. 10 



Closely associated with Taxionra and Pagetia is a single small 

 pygidium, which at present can be referred only to Tonkinella. This 

 pygidium is rather convex but flattened on top. Fusion has almost 

 eliminated the dorsal furrow and pleural grooves and furrows. All 

 are visible as shallow marks on the test. 



Locality 54s. 



Holotype.— U.S.N.M. No. 98530. 



