2 MR. E. T. NEWTON ON THE OCCURRENCE OF [Feb. I904, 



from the Coal-Measures of the United States, but was afterwards 

 recognized in beds of similar age in Russia and Australia. The 

 accompanying figure (fig. 1. below) of the first-described specimen 

 (Edestus minor) will call to mind the form of this ichthyodorulite, 

 which has been thought to be a dorsal defence. To it have also 

 been assigned various other functions in the economy of the fish to 

 which it belonged : its true nature, however, remains uncertain. 



The segmented character of Edestus minor is shown in this 

 figure ; and separate segments of this and other species have been 

 met with in North America, showing that each tooth was attached 

 to a firm base, elongated in one direction and grooved above for 

 the reception of the under part of a similar segment. Several such 

 segments were united in the original specimen. 



Fig. 1. — Side view of Edestus minor. (^ nat.size.) 

 [From Geol. Surv. Illinois, vol. iv (1870) pi. i, fig. 2.] 



A = Anterior, oldest segment. P> = Posterior, newest segment. 



It is now more than 48 years (August 1855) since Hitchcock [4] 

 first made known the remains of the remarkable fish from the 

 ' Coal-formation ' of Park County (Indiana), to which dewberry [8] 

 afterwards gave the name of Edestus minor. It was Leidy [5], 

 however, who proposed the generic name of Edestus for a large and 

 closely-allied form from the Coal-Measures of Arkansas, which he 

 described under the name of Edestus vorax. 



In the year 1870, Newberry and Worthen [9] made known 

 another species, Edestus Heinrichsii, from the Coal-Measures of 

 Illinois. Up to that time the genus had only been known in 

 North America ; but in 1878 Dr. H. Trautschold [10] recognized, 

 among the fossils described by him from Miachkova, near Moscow, 

 a single denticle, referable to this genus, which he named Edestus 

 protopirata ; and subsequently, in 1884 [12], the same writer 



