1887.] ON THE TELEOSTEAN GENUS RHACOLEPIS. 535 



4. On the Fossil Teleostean Genus Rhacolepis, Agass. By 

 A. Smith Woodward, F.Z.S., F.G.S., of the British 

 Museum (Natural History). 



[Eeceived June 7, 1887.] 



. (Plates XLVI. & XLVII.) 



Among the numerous fossil fishes named and briefly noticed by 

 Agassiz during the preparation of his great work ' Recherches sur 

 les Poissons Fossiles,' but reserved for adequate description in the 

 contemplated supplements which unfortunately never appeared, are 

 some interesting specimens from the north of Brazil, displaying 

 the characters of an extinct generic type, mentioned under the name 

 of Rhacolepis. Of these the British Museum now contains an 

 extensive series, enriched especially by the recent acquisition of the 

 Egerton and Enniskillen collections ; and as materials are thus 

 provided for a tolerably complete elucidation of the ancient fish they 

 represent, the present seems a favourable opportunity for completing 

 the original diagnoses. The majority of the fossils were actually 

 examined by Agassiz himself, and several bear his MS. labels, so that 

 it is possible to recognize the various species he intended to establish. 

 And a careful study of the whole series has lately revealed some 

 novel facts in regard to the affinities of the genus, which appear to 

 have hitherto escaped observation, and render it of considerable 

 interest to the zoologist. 



The fossil fishes in question, together with four or five other 

 genera, are discovered in calcareous nodules, of concretionary origin, 

 scattered upon the hill-sides in the neighbourhood of Barra do 

 Jardim, Serra de Araripe, North Brazil, and the first published 

 allusion to them appears to occur in the record of Spix and Martius's 

 travels at the beginning of the present century \ About 1840 many 

 specimens were collected by Mr. George Gardner, of Glasgow, who 

 submitted them to Agassiz, and briefly described the circumstances 

 under which they were met with^; and these, probably, form the 

 greater part of the Museum collection at the present time. Still 

 others were brought under Agassiz's notice by MM. F. Chabrillac 

 and Elie de Beaumont, and formed the subject of a lengthy report 

 published in the ' Comptes Rendus ' for 1844 \ Nearly thirty years 

 later, Professor C. F. Hartt added further remarks upon the 

 geological evidence as to the age of the nodules themselves * ; and 



^ J. B. von Spix and C. F. ^on Martins, 'Eeise in Brasilien,' 1823-31, Atlas, 

 pi. 22. fig. 5. 



- G. Gardner, " Geological Notes made during a Journey from the Coast 

 into the Interior of the Proiince of Ceara in the Korth of Brazil," Edinb. New 

 Phil. Journ. vol. xxx. 1841, pp. 75-82. — L. Agassiz, "On the Fossil Fishes 

 found bj' Mr. Gardner," ibid. p. 83. 



^ L. Agassiz, "Sur quelques poissons fossiles du Bresil," Comptes Eendus, 

 vol. xviii. (1844), pp. 1007-1015. 



* C. F. Harlt, ' Geology and Phj-sical Geography of Brazil (Thayer 

 Expedition),' 1870, chaps, xiii., xiv. jjasgim. 



