22 



R. cairnsi, with a like serration of the posterior margin in both. Other characters distinguish- 

 ing the two species are not observed, and the conclusion has been reached that there is no 

 real distinction between the two. The type of R. cairnsi is rather larger than the average sized 

 specimens of R. alberti. The striation parallel to the lower and front margins of the scales is 

 seen in the majority of the many specimens in the Geological Survey collection of the general 

 size of, and regarded as referable to, R. alberti, as well as in the two specimens shown by 

 Jackson in figures 2 and 3 of plate I. These last were regarded by Jackson as belonging 

 to one and the same species, but were not otherwise specifically determined. They are here 

 referred to R. alberti. Three other specimens, figures 4, 5, and 8, of plate II, not alluded to in 

 the text of Jackson's report, are evidently of this species. The originals of figures 4 and 5 

 consist of the posterior half of the fish only, consequently the anterior flank scales of these 

 particular specimens have not been seen; they evidently, however, belong to R. alberti, 

 rehance being placed on the characters displayed. The original of figure 8 includes scales 

 some distance in advance of the dorsal and anal fins, in which the characteristic striation of R. 

 alberti is revealed; its reference to this species is, therefore, considered proper. 



Elonichthys beowni (Jackson). 

 Plates IV, V, VI, VII, VIII, and IX. 



Palceoniscus brovmii, Jackson, 1851. Report on the Albert Coal Mine, etc., Boston, p. 22, 

 plate I, figs. 2 and 5, plate II, fig. 1, and plate I, fig. 4. 



Palceoniscus brovmii, Jackson, 1852. Description of five new species of fossil fishes, Proc. 

 Boston Soc. of Natural History, vol. IV, p. 138. 



Elonichthys brovmii, Traquair, 1877. Quart. Jour. Geol. Soc, vol. XXXIII, p. 553. 



Palceoniscus (Elonichthys) brovmii and Pi jacksonii, Dawson, 1877. Canadian Naturalist, 

 new series, vol. 8. p. 339. 



Palceoniscus {Elonichthys) brovmii and P. jacksonii, Dawson, 1878. Acadian Geology, 

 3rd edition, supplement, p. 101. 



Palceoniscus brownii and P. jacksonii, Newberry, 1889. Palseozoic Fishes of North America, 

 Monographs U. S. Geol. Surv.,. vol. XVI, p. 187. 



Elonichthys browni. Smith Woodward, 1891. Cat. Fossil Fishes, British Museum, part II, 

 p. 501, under doubtful and imperfectly defined species. 



The type of this species. No. 1961, of the collection of the Museum of Comparative Zoology, 

 Cambridge, Massachusetts, is from the Albert mines and was described by Dr. Jackson in 1851, 

 in his "Report on the Albert Mine, etc.," and in the year following, in the Proceedings of the 

 Boston Society of Natural History. It consists of the greater part of the fish, with the left 

 side exposed, in an admirable state of preservation, and gives very minute details of structure. 

 The specimen extends from close behind the head to a point some distance beyond the base of 

 the tail, so as to include about one-third of the body prolongation of the upper lobe of the tail 

 and the greater part of the lower lobe. The dorsal and anal fins are beautifully shown. From the 

 anterior end of the base of the anal fin forward, the specimen is imperfect below, and the pelvic 

 and pectoral fins are missing. The type specimen is well shown in Jackson's plate I, figure 2. 



