430 Davis— Om the Fossil Fish of the Cretaceous Formations of Scandinavia. 



that such being the case, the specimens were identical with those found in the 

 same strata, which have since been described by W. Von der Marck under the 

 generic name of Pelargorhynchus, which possesses a very long dorsal fin, and an 

 anal similar to the one described by Agassiz. 



In 1850, F. J. Pictet described three species of Dercetis from the Chalk of 

 Mount Lebanon. Two of these, namely, D. triqueter and D. tenuis^ were subse- 

 quently transferred in the " Nouvelles Recherches sur les Poissons Fossiles du 

 Mont. Libau." (1866), to the genus Leptotrachelus, Von der Marck ; and the addition 

 of specimens in a better state of preservation proved that the D. tenuis was derived 

 from the cervical region of D. triqueter. The third species Dercetis linguifer, 

 Pictet, known only from a fragment of the body, very imperfectly preserved, 

 was still doubtfully retained as representing the genus Dercetis in the Chalk of 

 Lebanon. 



In the description of the fossil fishes of Mount Lebanon* published in 1887, 

 it is remarked that since the year 1866 a considerable number of specimens of 

 Leptotrachelus have been obtained, and these differ much in size as well as in the 

 details of the form of the scutes ; and there can be no doubt that the figure given by 

 M. Pictet {op. cit., pi. ix., figs. 7, 8) is that of a portion of the body of a large fish 

 of the genus Leptotrachelus, and that it is the same species as those already 

 included in the species L. triqueter^ Pictet and Humbert. Since the above was 

 written I have had opportunities of examining the originals, in the Mantell 

 collection at the British Museum (Natural History Department), figured by 

 Professor Agassiz, and I am convinced that they are the same genus as the fish- 

 remains described as Leptotrachelus from Mount Lebanon, f This being so, it 

 becomes a question of synonomy, and as Dercetis was established about twenty 

 years before Leptotrachelus, it follows that the latter must be considered as a 

 synonym of Dercetis, Agass. The Lebanon fish-remains included under Lepto- 

 trachelus triqueter., Pictet and Humbert, will revert to the original designation of 

 Pictet, and be again Dercetis triqueter (including D. tenuis, Pictet, and D. linguifer, 

 Pictet), and the species Lej^totrachelus hakelensis,X Pictet and Humbert, and 

 L. gracilis,^ Davis, will be Dercetis hakelensis and D. gracilis. 



Dr. Anton Fritsch describes specimens from the chalk of Wehlowitzer Planer, 

 near Prague, which he has named Dercetis reussii,\\ Fritsch. The remains are 



* " Trans. Roy. Dublin Soc," ser. ii., vol. iii., p. 619. 



t See A. Smitli Woodward "On Fossils of the English Chalk."— Proc. Geol. Assoc, vol. x., p. 319. 

 1888. 



X "Nouv. Rech. s. Ics Poiss. Foss. du. Mt. Liban.," p. 98, pi. xiv., fig. 3. 1866. 



§ " Trans. Roy. Dubliu Soc," ser. ii., vol. iii., p. 623, pi. xxxvm., fig. 3. 1887. 



II " Die Reptilien und Fische der Bohmisohcn Krcideformation," p. 20, pi. ii., fig. 8 ; pi. iv., fig. 1 ; 

 pi. X., figs. 1, 6. 1878. 



