344 0. Holtedahl — Upper Cambrian Fauna 



in any respect differ from those shown in Walcott 's illus- 

 trations (see fig. 1, p. 103 of Cambrian Brachiopoda, U. S. 

 Geol. Surv. Mon. 51, 1912). Rather often, however, the 

 Arctic specimens show more acute cardinal angles (com- 

 pare the cast of the dorsal valve figured here) and more 

 numerous plications, these occurring rather evenly dis- 

 tributed both over sinus and fold and the lateral parts. 

 This species reminds one strikingly of a small Platystro- 

 phia biforata, the dorsal valves being also Spirifer -like. 

 The rather broad and evenly plicated type of this 

 extremely variable Arctic species is very near to another 

 North American species of the same genus, H. lesleyi 

 Walcott, from the Upper Cambrian of Utah (see op. cit., 

 text fig. 75). In the natural casts of the interior such as 

 are commonly found (the interior characters can also 

 easily be shown artificially by using acid), we notice, the 

 typical characters of the Syntrophiidse. As to whether 

 the interior of this Arctic species corresponds in every 

 detail to that of the American forms mentioned, I can not 

 tell, as I have seen no illustrations of the interiors of the 

 latter. 



Besides the Huenella two orthoid brachiopods occur, 

 one of which may be identical with Eoorthis? melita Hall 

 and Whitfield, while the other is of the type of Eoorthis 

 ivichitaensis Walcott so far as the dorsal valves are con- 

 cerned ; the ventral valves in the latter, however, do not 

 have the even, gentle convexity of Eoorthis, but are flat, 

 with elevated umbones reaching rather far beyond the 

 hinge-line. In addition, there are fragments of inarticu- 

 late brachiopods, a Hyolitlms, and traces of gastropods 

 (of the type of Pelagiella pagoda Walcott). Fragments 

 of trilobites also occur, commonly the central part of 

 cephalons. At least four species are represented: one is 

 probably a Ptychoparia, another a Solenopleura of a 

 rather extraordinary type, with the frontal rim very 

 broad and very prominent. In addition occur fragments 

 of a Ptychaspis sp. and of a small Illcenus-like form, with 

 the dorsal furrows widely spaced and developed only in 

 the posterior part of the head; the occipital furrow is 

 well developed, differing in this respect from congeneric 

 forms. 



From the lighter colored fossiliferous calcareous sand- 

 stone a very large amount of material was collected, 



