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XX. Description of the Lepidosiren annectens. By Richard Owen, Esq., 

 F.R.S. F.L.S. F.G.S., Hunterian Professor in the Royal College of Surgeons, 

 London. 



Read April 2nd, 1839. 



XhE animal about to be describeci belongs to a genus founded and referred 

 to the class Amphibia by Fitzinger*, for the reception of an allied species 

 discovered by Dr. Natterer in the river Amazon, and of which a brief account 

 has been given by that excellent naturalist in the Annals of the Museum of 

 Viennaf under the name of Lepidosiren paradoxa, a new genus of the family 

 of Fish-like or Perennibranchiate Reptiles, with the following characters : 



" Corpus anguillseforme totum squamatum. Pedes quatuor, valde distantes, 

 adactyli." 



In these and most of the other characteristics detailed in the text of 

 Dr. Natterer the present species closely agrees with the Lepidosiren paradoxa ; 

 the principal differences occur in the relative proportions of the head, trunk 

 and rudimental filamentary extremities. 



The whole length of the Lepidosiren paradoxa includes eleven lengths of 

 the head, measured from the end of the mouth to the gill-openings ; in the 

 present species the total length of the animal includes little more than six 

 lengths of the head. In the L. paradoxa the length of the body anterior 

 to the commencement of the dorsal fin includes four and a half lengths 

 of the head : in the L. annectens there are only two lengths of the head be- 

 fore the dorsal fin commences. The length of the anterior extremity is one- 

 twelfth that of the entire body in the L. paradoxa : it is only one-sixth of 

 the same length in' L. annectens. This species is therefore distinguished 

 from the Lepidosiren paradoxa by the shorter relative length of the trunk as 



* Frorieps Notizen, vol. 1. p. 90; and Wiegmann's Archiv., 1837. p. 232. 



t " Lepidosiren paradoxa, eine neue Gattung, aus der Familie der Fischahnlichen Reptilien, Toyj 

 Johann Natterer, Annalen des Wiener Museums der Naturgeschichte, .1837, ii. p. 165," 



VOL. XVIII. 2 X 



