76 REPORT— 1860. 



author contended that it is not applicable to the celebrated case of Jorullo, as described 

 by Humboldt, nor yet to the volcanic islands thrown up in deep water at various times 

 during the historical period. 



He was also disposed to refer the four trachytic Puys near Clermont, in Auvergne, 

 as well as the still loftier Cones composed of the same material in the Andes, which 

 Humboldt describes, rather to the upheaval of a softened mass of rock, than to the 

 outburst of liquid lava. 



He appealed also to the crater-lakes in the Eifel country and elsewhere, as furnish- 

 ing cases of upheaval, even where no lava had been ejected; and argued, that so long 

 as the idea of paroxysmal action continued to be entertained with reference to rocks 

 in general, it was probable that volcanic countries, above all others, would be subject 

 to such operations. 



On the Mode of Flight of the Pteroductyles of the Coprolite Bed near Cam- 

 bridge. By the Rev. J. B. P. Dennis, F.G.S. 



Coprolitic remains of Pterodactyle bone have afforded an opportunity of studying its 

 microscopic characters, and this had led to the present attempt to show from the ana- 

 logy of other flying animals, from the different modes of flight among birds, from the 

 apparent adjustment of the haversian canals thereunto, and the harmonious perfection 

 of the skeleton with the adaptation of the pectoral muscle to the same (so that even the 

 humeral process of its attachment has its marked characteristics), that these and other 

 analogies lead to the inference that considerable knowledge even of the mode of flight 

 of this extinct reptile may be obtained from the study of its microscopical bone struc- 

 ture. In elucidation of this subject, a brief account was given of the structure of the 

 wing-bones of a bird, and of the mode of flight of the Gull, a bird distinguished for 

 its elasticity and endurance on the wing, and in other respects very suitable for illus- 

 trating the subject. 



A description was then given of fragments of Pterodactyle bone obtained by Mr. 

 Barrett from the coprolite bed, most of which were portions of wing-bones of very 

 thin texture. It was also shown that the Pterodactyle required not to be encumbered 

 with muscular legs, and thus the vastus was only sufficiently developed to enable the 

 animal to spring from the ground preparatory to flight (as the form of the femur also 

 seemed to indicate); also the biceps, semitendinosus, &c, or their analogues, did not 

 require any great development; while the gastrocnemius, as it would assist in the 

 spring, was probably on that account fairly represented. The pectoral muscle, follow- 

 ing the saurian type, must have been less voluminous than that of birds, flatter, with 

 its greatest development in front, and in position comparing somewhat with that 

 muscle in gulls and owls, birds of elastic but not rapid flight. The Pterodactyle was 

 also shown to agree more with birds than with bats, especially in its omoplate, while 

 the absence of a fercula implied no similar volume of muscle ; the bones in like man- 

 ner were permeated by air, or if some were not, they were yet filled with a light fatty 

 substance or marrow to give additional strength to their light texture ; and though the 

 natural weakness of its muscular powers was considerable in comparison with birds, 

 yet this was balanced by an extremeh' light framework, the weight of which predomi- 

 nated in front, where the muscular force was more directly antagonistic; and above all, the 

 admirable microscopic structure of its bone eminently conduced to its powers of flight. 

 Delicate in the extreme to the unassisted eye, when examined under the microscope, 

 the bone is found to contain numerous and large haversian canals in a very marked 

 degree, comparing in their arrangement with those seen in the wing-bones of gulls; 

 also lacunas well displayed, larger than those of a bird of flight, long and fusiform. 

 From this correspondence of the characters of the haversian canals, of which illustra- 

 tions were given, an inference seems capable of being drawn in reference to the flight 

 of these large Pterodactyles, which, if they did not possess the dash of the falcon or the 

 impetuosity of the wood-pigeon, yet sailed gracefully over primaeval seas with a light- 

 ness and buoyancy, as it would seem, analogous in some degree at least to the con- 

 spicuous grace of the gulls, which are the present ornament of our coasts. So in every 

 respect is seen the wisdom displayed in the adaptation of means, each inadequate 

 in itself, and the result is the production of one of the strangest anomalies, of 

 which, if we had not had the clearest testimony, the imagination would have failed to 

 picture, — a true Pterosaurian, in some respects perhaps more wonderful in its con- 

 struction than bats or even birds, and being as fully capable of flight as they, teaching 



