THE LOWER EMBAR OF WYOMING 653 



Four imperfect specimens and several fragments of this species 

 were collected. They agree with St. John's excellent description 

 of 1872 except in two minor details. The striae on the main cone 

 project nearly to the summit instead of only half-way. St. John 

 does not figure any specimens with the summit of the cone pre- 

 served, and this part of the description probably came from New- 

 berry and Worthen's description of Cladodus mortifer. The lateral 

 denticles do not have sharp cutting edges except as these are formed 

 by one more prominent ridge on each side. 



This species has been reported from the Upper Coal Measures 

 near Springfield, Illinois, southwestern Iowa, Manhattan, Kansas, 

 Nebraska City and Table Rock, Nebraska, and from the Coal 

 Measures of Indiana and the Permo-Carboniferous of Roca, 

 Nebraska. 



Trautschold 1 identified a form from the Moscowian as Cladodus 

 lamnoides Newberry and Worthen, but his figures and descriptions 

 indicate C. occidentalism and, as other species are common to the 

 Moscowian and the Upper Pennsylvanian of the Mississippi 

 Valley, this is probably the correct reference. 



ICHTHYODORULITES 



Ctenacanthus browni n. sp. (PI. IV, Fig. 7, and Text-Fig. 6) 



The holotype is an imperfect spine. The part preserved is 

 13 cm. long, 2 cm. wide at the outer end, and 27 mm. wide at the 

 inner. None of the inserted portion is retained. The curvature 

 is very slight. The pulp cavity at the outer end is 7 mm. by 2 mm., 

 and at the inner end 11 mm. by 4 mm. The surface is ornamented 

 by 20 to 23 longitudinal, smooth, closely spaced costae that are 

 slightly wider than the intercostal spaces and are imperfectly 

 divided into three sets. In the anterior set there are 4 costae and 

 4 intercostal spaces in 5 mm., in the second there are 6 costae and 

 6 intercostal spaces in 5 mm., and in the third 7 or 8 in 5 mm. The 

 costae in the first set are high and narrow, in the second set narrower 

 and about half as high, and in the third of about the same width 

 as in the second, but very low and becoming obsolete at the back. 

 The posterior face of the spine is slightly excavated, contains closely 



1 "Die Kalkbruche von Mjatschkowa: Eine Monographie des obern Bergkalks," 

 Nouv. Mem. Soc. Imp. Natur. Moscow, XIII, 10-12, Table I, Figs. 3a-e. 



