AMERICAN ZOOLOGISTS AND EVOLUTION. 493 



Dr. Spencer Trotter* has made a study of the collar-boue and its 

 significance, in which he accounts for its presence or absence in mam- 

 malia by correlating it with the life-habits of the animal in the use of 

 the fore-limb. He says : " Every fully-developed tissue in an organism 

 is needed, or it would not be there ; and just so soon as by increasing 

 change in life and habits it becomes a factor of less and less importance 

 to the animal, it fails more and more to attain its former standard of 

 development, and in time falls back to the primitive condition from 

 which it arose and finally disappears." 



Many new and interesting facts have been added sustaining the 

 afiinity between the birds and reptiles. Professor O. C. Marsh f made a 

 careful study of the Archffiopteryx in the British Museum. The new 

 points he has added bring out still more strongly the extraordinary 

 characters blended in this creature. Among other features he discov- 

 ered the separate condition of the pelvic bones, and shows that while 

 it must be considered a bird, yet it has true teeth, bi-concave vertebrae, 

 three separate fingers in each hand, all furnished with claws, meta- 

 tarsals and metacarpals, equally unanchylosed and the pelvic bones 

 separate, as already mentioned. 



Dr. J. Amory Jeffries,J in the study of the claws and spurs on 

 birds' wings, has presented an interesting table showing the number 

 of phalanges in each finger, from the highest to the lowest family of 

 birds, with the presence or absence of claws recorded for each finger. 

 This table shows very clearly that the higher birds have fewer pha- 

 langes and no claws, and as one approaches the lower families the 

 phalanges increase in number, the first finger having two phalanges, 

 and the second and third fingers being tipped with claws. 



In a brief study of the tarsus of low aquatic birds,* made with 

 special reference to the interpretation of the ascending process of the 

 astragalus with the intermedium of reptiles, I observed a separate 

 center of ossification for this so-called process, observed its unques- 

 tionable position between the tibiale and fibulare, its increase in size 

 with the growth of the bird, and its final anchylosis with the proximal 

 tarsal bones. In the bones of a young Dinornis, which through the 

 courtesy of Dr. Henry Woodward I was kindly permitted to examine 

 in the British Museum, the ascending process was large and conspicu- 

 ous and fii-mly anchylosed with the coossified tarsals to the distal end 

 of the tibia. Professor Marsh, || in a study of the metartasal bones of 

 Ceratosaurus, a Dinosaur discovered by him, found that the metatar- 

 sals coossified in the same manner as those of the penguin. 



The question as to the existence of a sternum in Dinosaurian 



* " American Naturalist," vol. xix, p. 1172. 



■f "American Journal of Science and Arts," vol. xxii, p. 338. 



X " Proceedings of the British Society of Natural History," vol. xxi, p. 301. 



* "Anniversary Memoirs of the British Society of Natural History," 1880. 

 II "American Journal of Science and Arts," vol. xxviii, p. 161. 



