NO. 2177. FOSSIL FISHES IN NATIONAL MUSEUM— EASTMAN. 275 



are twice as high as long. . . . These high scales gradually become 

 reduced in height, so that those below the dorsal fin are about as 

 high as long," 



Doctor Hay remarks further that in his material "the caudal fin 

 is fully one-third the total length of the fish, is deeply forked and has 

 the prolongation of the body covered with pointed scales carried out 

 apparently to its very tip. . . . Along the upper lobe of the tail are 

 numerous striated fulcra. These diminish in height each way from 

 the middle of the lobe." As regards contour of the back the same 

 author observes: 



The body appears to have been somewhat elevated immediately under the dorsal 

 fin, the latter being thus lifted somewhat. The sides of this elevation are covered 

 with two rows, an upper and a lower, of narrow, rather long scales, which are directed 

 parallel with the fin rays. 



Probably to this species should be referred two specimens belonging 

 to the United States National Museum collection, which are shown of 

 shghtly larger than the natural size in the accompanying plates (pi. 

 9, fig. 3; pi. 10, fig. 3). The form of body is, however, more slender 

 than in the figured example of E. Jiypsilejns and E. peltigerus, and the 

 dorsal and anal fins are relatively less elevated and more triangular. 

 The anal fin-rays decrease more rapidh^ in depth behind, and there 

 is a wider interval between the anal and caudal fins than is the case 

 in those examples of E. Jiypsilepis or E. peltigerus which have come 

 under the writer's observation. There is, however, substantial 

 agreement in the number of rays of all the fins, and such difl'erences 

 as have been noted do not appear to waiTant the recognition of a dis- 

 tinct species upon the evidence of these examples. 



Formation and locality. — Coal Measures; Mazon Creek. 



ELONICHTHYS PERPENNATUS Eastman. 



Plate 9, fig. 1. 



Elonichthys perpennatus Eastman, Journ. Geol., vol. 10, 1902, p. 539, text fig. 4; 

 Bull. Mus. Comp. Zool., vol. 39, 1903, p. 190, pi. 5, fig. 49. 



This is a very small species, having a total length of less than 4 cm., 

 of wliich the head occupies a little less than one-fourth. The fins are 

 extremely well developed, the pectoral unusually long, and anal with 

 much extended base line. The fulcra are minute, scales relatively 

 small, obliquely striated; dorsal ridge scales enlarged 



Our knowledge of this gracefully formed and highly ornamented 

 small species has hitherto been confined to the original holotype, 

 now preserved in the Museum of Comparative Zoology at Harvard 

 College. A second example, which seems referable to this species, 

 is that shown in plate 9, figure 1, It is in counterpart, and bears the 

 U.S.N.M. catalogue number 4326. The paired fins have become 



