Dr. H. Burmeister on Saurocetes argentinus. 51 



kled with cinereous, and with the apex truncate. Below with 

 a broad black shining stripe in tlje middle. 

 Only one specimen. In my collection. 



Ancylonotus, Cast., Lac. 

 Ancylonotus tribulus, Fab. Syst. El. ii. 281. 



This well-known African species does not seem to be so 

 common at Old Calabar as elsewhere on the west coast. It 

 has only come once or twice. 



fTo be continued.] 



VI. — On Saurocetes argentinus, a new Ty])G q/Zeuglodontidas. 

 By Dr. Hermann Burmeister. 



[Plate I.] 



The public museum of Buenos Ayres has lately received the 

 under jaw of a very interesting fossil mammalian, which I 

 beg leave to describe, under the above denomination, as an 

 entirely new type belonging to the curious tribe of Zeuglodon- 

 tida3. This specimen was generously presented to the mu- 

 seum by Dr. D. Manuel Montes de Oca, Professor of Physiology 

 in the Medical Faculty of Buenos Ayres. That patriotic gentle- 

 man having noticed the great interest taken by me in it 

 when looking over his valuable collection, offered me the 

 opportunity of examining the bones and describing them for 

 the benefit of science, which I am glad to acknowledge here 

 with well-merited thanks. 



Respecting the locality where the fossil was found, M. 

 Montes de Oca could say nothing ; he received it from one of 

 his patients, who brought him the bones, broken as they are, 

 from the interior of the country, as a contribution to his col- 

 lection. But the adherent remains of the formation in which 

 the bone was discovered prove very clearly that the fossil 

 was taken out of a sandy bed of the great Tertiary fornyation on 

 the shores of the river Parana, which D'Orbigny has named 

 the " Formation imtmjonienne.^'' This formation, described 

 by Darwin, D'Orbigny, Bravard, and myself*, is chiefly a 

 marine deposit mixed with beds of fresliAvater deposition, 

 wherein are found many bones of freshwater fishes (Silurida3), 

 of Crocodilida?, and even of terrestrial Mammalia. We have 

 in the museum of Buenos Ayres bones of all these animals, 



* Reise durch die La Plata-Staaten, torn. i. p. 410 (Ilalle, 1861, 8vo) ; 

 Anales del Museo Publico do Bueuos Aires, torn. i. p. 114. 



4* 



