3 H THE POPULAR SCIENCE MONTHLY. 



One of the most interesting points determined during my inves- 

 tigation of Archceopteryx was the separate condition of the pelvic 

 bones. In all other known adult birds, recent and extinct, the three 

 pelvic elements, ilium, ischium, and pubis, are firmly anchylosed. In 

 young birds these bones are separate, and in all known Dinosaurian 

 reptiles they are also distinct. This point may, perhaps, be made 

 clearer by referring to the two diagrams before you, which I owe to 

 the kindness of my friend Dr. Woodward, of the British Museum, 

 who also gave me excellent facilities for examining the Archceopteryx 

 under his care. In the first diagram, we have represented the pelvis 

 of an American Jurassic Dinosaur allied to Tguanodon, and here the 

 pelvic bones are distinct. The second diagram is an enlarged view 

 of the pelvis of the Archceopteryx in the British Museum, and here too 

 the ilium is seen separate from the ischium and pubis. 



In birds the fibula is usually incomplete below, but it may be co- 

 ossified with the side of the tibia. In the typical Dinosaurs, Iguano- 

 don, for example, the fibula at its distal end stands in front of the 

 tibia, and this is exactly its position in Archceopteryx, an interesting 

 point not before seen in birds. 



The metatarsal bones of Archoeopteryx show, on the outer face at 

 least, deep grooves between the three elements, which imply that the 

 latter are distinct, or unite late together. The free metacarpal and 

 separate pelvic bones would also suggest distinct metatarsals, al- 

 though they naturally would be placed closely together, so as to ap- 

 pear connate. 



Among other points of interest in Archceopteryx may be men- 

 tioned the brain-cast, which shows that the brain, although compara- 

 tively small, was like that of a bird, and not that of a Dinosaurian 

 reptile. It resembles in form the brain-cast of Laopteryx, an Ameri- 

 can Jurassic bird, which I have recently described. The brain of 

 both these birds appears to have been of a somewhat higher grade 

 than that of Hcsperorn/'s, but this may have been due to the fact 

 that the latter was an aquatic form, while the Jurassic species were 

 land birds. 



As the Dinosaaria are now generally considered the nearest allies 

 to birds, it was interesting to find, in those investigated, many points 

 of resemblance to the latter class. Compsognathus, for example, 

 shows in its extremities a striking similarity to Archceopteryx. The 

 three clawed digits of the manus correspond closely with those of 

 that melius ; although the bones are of different proportions. The 

 hind-feet also have essentially the same structure in both. The verte- 

 bra?, however, and the pelvic bones of Compsognathus differ materi- 

 ally from those of Archceopteryx, and the two forms are in reality 

 widely separated. While examining the Compsognathus skeleton, I 

 detected in the abdominal cavity the remains of a small reptile which 

 had not been previously observed. The size and position of this in- 



