104 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 75 



Genus LEIOSTEGIUM Raymond 



Leiostcgiuni Raymond, 1913, Bull. No. i, Victoria Memorial Museum, p. 68. 

 Observations. — The genus Leiostcgium founded by Raymond on 

 Billings' Bathyurus quadratus hitherto has had a few species referred 

 to it. At the present time in the study of the Ozarkian faunas 22 

 additional species have been determined or referred to the genus. 

 Furthermore, three new genera have been erected to include the 

 many forms grouping themselves about characters not belonging to 

 Leiostegimn. The name Ptychostegiuni appeared in certain published 

 faunal lists, but further study proved that the characters used in the 

 preliminary determinations were not of sufficient importance to be 

 of generic rank. 



LEIOSTEGIUM MANITOUENSIS, new species 



Plate 23, figs. 12-19 



Observations.— This species is characterized by its quadrate gla- 

 bella with the two pits at each side in front, together with the size 

 and position of the eyes and the small frontal border. Free cheeks 

 fairly wide, all with a long genal spine. Facial suture intramarginal 

 for a short distance. The doublure of the free cheeks is a continuous 

 piece of even width across the front of the head. 



The associated pygidium is not very imlike that of Belief ontia (see 

 figs. 10, II, pi. 23), but it can be distinguished by its more definite 

 border, definite rings on the axis and by its more subtriangular 

 outline. 



Formation and locality. — Ozarkian: (187) Basal Manitou lime- 

 stone, two miles (3.2 km.) below Manitou Park Hotel, Colorado: 

 Chushina formation, Mt. Extinguisher near Mt. Robson. British 

 Columbia (6iq). 



Genus MALADIA Walcott 

 Maladia Walcott, 1924, Smithsonian Misc. Coll., Vol. 75, No. 2, p. 59. 



The cranidium of Maladia is somewhat quadrate in shape. The 

 glabella is outlined by the dorsal furrow and a wide, deep occipital 

 ftirrow. Eyes large. Free cheeks rounded and without genal spines. 

 Pygidium with spinose border, with a very high axis. Pleurae are 

 well fused. 



This genus with its strongly defined cranidium and associated 

 pygidium (same at several localities) is related by the course of its 

 facial sutures, free cheeks, and pygidium with Eurckia, and to a much 

 less extent with Corbinia, but is clearly not congeneric with either. 



Genotype. — Maladia americana Walcott. 



Range. — Upper Cambrian: Ovid formation, Idaho. Grand Can- 

 yon, Arizona. 



