the Palceontologia Argentina. 323 



1. — This Memoir is of peculiar interest, since it contains a 

 description of the first Dinosaurs recorded from South America. 

 These are referred to three genera : Titanosaurus, Argyrosauriis, and 

 Microccelus, the first two of which belong to the Sauropodous group, 

 while the third is of doubtful position. The remains ascribed to 

 Titanosaurus, a genus originally founded on some caudal vertebrJB 

 from the Lameta beds (Lower Cretaceous) of India, are provisionally 

 referred to two species, and tend to show that, in some respects, 

 e.g. the biconvex first caudal vertebra, this form approached the 

 Crocodilia more nearly than any other Dinosaur at present known. 

 Its wide distribution, occurring as it does in India, England, and 

 South America, is also notable, but the discovery of further remains 

 may show that the relationship between the species from these 

 various regions is by no means so close as it now appears. The 

 second genus, Argyrosaurus, is new, and is founded on a beautifully 

 preserved fore-limb, the possessor of which must have rivalled the 

 largest known Dinosaurs in size. The third genus, Microccelus, is 

 also new and is represented only by a few isolated bones. A small 

 dorsal vertebra is doubtfully referred to a member of the Theropodous 

 group. The exact age of the deposits in which these reptilian remains 

 are found is doubtful, but is most probably Lower Cretaceous. 



The second Memoir, "On Cetacean Skulls from Patagonia," is 

 valuable for the light which it throws on some points in the 

 phylogeny of the group in question. The first form described is 

 a small baleen whale, referred to the European genus Cetotherium 

 and remarkable for the large size of the nasals, which partly roof 

 in the narial chamber. Two other European genera, Physodon and 

 Eoplocetus (Paracetus), are represented by skulls, hitherto unknown; 

 and a new family, the PhysodontidiB, is instituted for their reception, 

 from the fact that the upper jaw possesses teeth, thus differing from 

 that of the nearly related sperm whales. The Squalodontidse are 

 represented by a new genus, Prosqualodon, in which the nasals are 

 better developed than in Squalodon. Moreover, the mandibular 

 symphysis is shorter and the dentition is different, there being 

 five (? six) molars and four premolars. The most interesting form 

 of all is referred to a new genus, Argyrocetus, which is made the 

 type of a family, the Argyrocetidae ; it is said to be most nearly 

 related to the Platanistidge. The notable characteristics of this 

 genus are the possession of large square nasals and prominent 

 occipital condyles, and the complete symmetry of the skull. The 

 nasal opening may have been double. The deposits in which all 

 these remains were found are not later than the Miocene and may 

 be Upper Eocene. 



In the third Memoir, "A Study of the Extinct Ungulates of 

 Argentina," the author states that his " main object has been to 

 find out how many of the numerous genera that have been named 

 of late years on the evidence of more or less satisfactory materials 

 were really entitled to stand, and also to elucidate in some degree 

 their natural affinities." He has, however, passed over such genera 

 as are founded on insufficient evidence or are not represented in the 



