170 Notices of Memoirs — L. Dollo — Teleosteans of Belgium. 



fossil to be specifically identical with the so-called Gavialis inner o- 

 rhynchus, made known by Gervais from the Upper Cretaceous of 

 Mt. Aime ; and Dr. Koken further agrees with Dr. Leidy in 

 referring- this European type to the genus Thorn cosaur us, which 

 was originally founded upon a cranium from the Upper Cretaceous 

 of New Jersey, U.S.A. The type-species of Tlioracosaurus is said 

 to possess antorhital vacuities, but these are not observed in the 

 Maastricht fossil, and the author suggests that accidental fractures 

 may have been mistaken for such in the New Jersey skull. Detailed 

 comparisons are instituted, and the subject developes into an interest- 

 ing treatise on the classification of the Crocodilia. Dr. Koken 

 considers that Tlioracosaurus, Tomistoma, and Gavialis are direct 

 descendants of the Macrorhyncbidae, Gavialis being the most 

 specialized form of this group, and having no intimate connection 

 with the Teleosauridse, which are regarded as a marine family 

 that became extinct before the end of Mesozoic times. A long 

 statement of anatomical facts leads to the conclusion that the 

 Parasuchia are as nearly related to the Lizards as to the Croco- 

 diles ; and it is suggested that they may appropriately rank as 

 equivalent to a group comprising all other so-called Crocodiles, 

 an order Crocodiloidea being instituted, with the two suborders 

 Parasuchia and Crocodilia. Agreeing with Lydekker, Dr. Koken 

 considers that there is no satisfactory line of demarcation between 

 the Mesosuchia and Eusuchia ; but the arrangement adopted in the 

 British Museum catalogue is characterized as unnatural and a purely 

 stratigraphical classification. Amphicoelian and proccelian genera 

 are now placed together in each of the three surviving families of 

 Crocodilidse, Alligatoridaa, and Macrorhynchidse ; the first arising 

 with Bemissartia, the second with Gonioplwlis, and the third with 

 Pholiclosaurus, etc., this again subdividing into Tomistoinatinaa and 

 Gavialinaa. Incidentally it is pointed out that sclerotic plates are 

 not peculiar to Geosaurus, as once stated, but that feeble ossifications 

 occur also in the recent Alligator ; and there is some evidence of 

 Cricosaurus having possessed a dermal armour, thus differing in 

 that respect from Geosaurus, as described. In a postscript, the 

 author notes with satisfaction some recent observations of Mr. 

 Hulke (Proc. Zool. Soc, 1888), which are in accordance with his 

 own views. A. S. W. 



III. — Premiere Note sur les Teleosteens du Bruxellien (Eocene 

 moyen) de la Belgique. By Louis Dollo. Bull. Soc. Beige 

 Geol., Paleont., Hydrol., vol iii. (1889), pp. 218-226. 



M DOLLO discusses the spines and other fragments of a Siluroid 

 , fish met with in the Bruxellian Beds of Belgium, already 

 recorded under the name of Silurus Egertoni, Dixon. He concludes 

 that these remains are specifically identical with the English Brack - 

 lesham fossils originally thus named, and agrees with the recent 

 determination of the species as a member of the genus Arius. 



