31 



THE GEOLOGIST. 



or three digits in the hand. There was no trace of the fifth digit of the 

 winged reptile. Of the pelvis, a bone on the left side was preserved, bear- 

 ing a resemblance to the iliac bone of a bird, and with a sinuous border ; 

 its exposed surface was smooth and polished, and 7 lines broad. The an- 

 tero-interior surface of the ilium and the coalesced ischium terminate ab- 

 ruptly and obtusely, as in a young bird. The ischium, behind the aceta- 

 bulum, shows a vacuity between itself and the pubis, the obturator fora- 

 men being as large as in birds. In the Pterodactyle the ilium is shorter, 

 the ischium being subtriangular, joining with the ilium. The sacrum was 

 a confused mass of vertebra?, in which six or seven short transverse pro- 

 cesses can be seen. The conditions under which the skeleton was found 

 reminded Professor Owen of the carcass of a gull, which, after having been 

 a prey to some carnivore, which had removed all the soft parts, and per- 

 haps the head, had left nothing but the bony legs, and the indigestible quill- 

 feathers. The tarso-metatarsal, at its distal end, exhibited a trifid, tro- 

 chlear, articular surface, supporting three toes. The shaft of the femur was 

 long and thin, while a procnemial ridge was present on the tibia. The size of 

 the procnemial ridge is variable in birds ; in Archgeopteryx it was as large as 

 in Falco irivirgatus and in most Yolitores. The thigh was longer than in 

 the majority of birds. The proportions of the toes accord with the inses- 

 sorial, and not with the scansorial type of foot. Pew of the bones are in 

 a condition to permit minute comparison of their texture. The osseous 

 remains having been exposed to a disintegrating action by which the 

 phosphate had been converted into carbonate of lime, and in the interior 

 of the bones crystallized spar has been deposited. Each vertebra of the 

 tail supports a pair of plumes. The fossil differed from all known existing 

 birds in having a tail composed of twenty vertebrse. But the tail is essen- 

 tially a variable character ; there are long-tailed bats and short-tailed bats, 

 long-tailed rodents and short-tailed rodents, long-tailed Pterodactyles and 

 short-tailed Pterodactyles. It is now manifest that there existed, at the 

 period of the deposition of the Oxfordian strata,, a bird exhibiting the persist- 

 ent embryonal or generalized character of the tail, as opposed to the special- 

 ized condition of the tails of existing birds, in which the terminal vertebra? 

 have coalesced. All embryo birds exhibit the caudals distinct, the greatest 

 number of separate caudals being exemplified by the ostrich. The develop- 

 mental process undergone by the bird is similar in nature to that through 

 which the fish passes in its transition from the heterocercal stage, through 

 which it usualty passes, to the homocercal. The probability of the presence 

 of a single unguiculate digit, as in the wings of Pteropus, would, if demon- 

 strated, exhibit a similar retention of an embryonal and transitory character. 

 The Archseopteryx was unequivocally a bird ; and, by the law of correlation, 

 we might infer that it was destitute of fleshy lips, that its feathers were 

 preened by a horny edentulous beak, and that the shape of the breast-bone 

 was such as was possessed by animals capable of flight. The President 

 moved a vote of thanks; and, calling for remarks, the Duke of Argyll 

 hoped that Mr. Gould would offer some opinion on the fossil. Mr. Gould, 

 P.E.S., considered that the remains indicated a terrestrial form of bird, 

 with wing feathers not adapted for flight, as in the Apteryx, or in the 

 black rail of New Zealand. Had the hind foot alone been shown to any 

 ornithologist, he would have been entitled to infer that it was a bird— a 

 fact which Mr. Gould had doubted up to the previous day, but which he 

 now felt constrained to admit. Dr. Carpenter, P.K.S., coincided in Pro- 

 fessor Owen's remarks respecting the more generalized vertebrate type of 

 the specimen, and remarked on the futility of negative evidence in geolo- 

 gical discussion. Professor Owen pointed out that the shape of the pec- 



