1870."] Geology and Palaeontology. 271 



These curious buckler-Leaded fishes are certainly among tLe 

 most interesting as they are undoubtedly the very earliest forms of 

 tLe vertebrate type with wLicL we are acquainted. 



One head-shield figured measures more than 6 inches across 

 and above 7 inches in length. 



Mr. Fielding has most successfully rendered the fine and deli- 

 cate striae on the plates of Pteraspis in plates vi. and vii. The 

 histology of these fish-plates is carefully worked out and most beau- 

 tifully Illustrated by Tufien West. 



Professor Owen's monograph on the Lias Pterosauria deserves 

 more than a passing notice. 



For the first time we see before us an entire British Pterodac- 

 tyle in his Dimorphodon macronyx, not restored at random, but 

 carefully put together bone by bone from the three specimens in 

 the British Museum. Dimorphodon, as we thus know it, has a 

 long and slender tail firmly set and imbedded in ossified tendons, 

 rendering it apparently an inflexible rudder ; the hind limbs are 

 well developed, as also are the claws and the wing-fingers. The 

 head is very large, with beautiful contrivances for lightening it by 

 means of large vacuities ; the jaws are armed with larger laniary 

 teeth, and rows of more regular minute and pointed teeth. There 

 is no evidence that this species had a beak or horny termination to 

 its jaws as Yon Meyer believes to have been the case in Bham- 

 pliorhynchus from the Solenhofen beds. 



Upon the affinities of the Pterosauria Professor Owen is at issue 

 with Professor Huxley, the former arguing against their Ornithic 

 and in favour of their Beptilian afiinities, the latter placing them 

 in the same group with the Dincsauria, the Crocoditia, and the 

 Anomodontia (called by Professor Huxley the Omithoscelida), 

 the most bird-like of the Beptilia. 



Professor Owen argues that the possession of feathers and warm 

 blood are essentially bird-like attributes, whilst the absence of 

 feathers in the Pterosauria proves them to have been cold-blooded 

 reptiles. The Cockchafer is cited by Professor Owen to prove 

 that powerful flight may co-exist with cold blood ; but if we could 

 compare the bulk of the insect with that of the Pterodactyle, there 

 seems little doubt that the temperature would also increase with 

 the size of the animal, and in proportion to the increased muscular 

 work required to be accomplished. 



We deprecate the tone adopted by the author in his critical 

 review of Professor Huxley's observations,* and earnestly hope it 

 may not be found in any future monographs. 



The concluding Monograph, also by Professor Owen, treats of 

 the Cetacean remains, occurring in the Bed Crag, belonging to the 

 genus Ziphius of Cuvier. These curious rostra are found in tole- 



* P. 74. 



