288 Correspondence. lAprll 



service to him in this country in securing the data of literature and other 

 material. 



Mr. Heilmann still stands in need of some similar assistance, a part of 

 which I have been unable to secure for him in Washington. The Utera- 

 ture gives no trouble as we have large libraries here; but I should very 

 much like to borrow, for short periods of time and for the purpose of mak- 

 ing photographs, some of the following specimens, namely, (1) a good 

 example of a nestling Hoatzin {Opisthocomus cristatus) in alcohol; (2) 

 specimens, also in alcohol, of the male reproductive organs of any of the 

 ratite birds but especially of the common ostrich; (3) microscopic slides 

 of the spermatozoa of any of the Ratitoe or of reptiles; (4) alcoholic speci- 

 mens of anything showing the pecten of the eye in birds or reptiles, and (5) 

 any other specimens along similar lines. For the loan of such material I 

 will be glad to meet the expense both ways, and full credit will be given to 

 the individual or institution loaning it in Mr. Heilmann's forthcoming work, 

 which is now in hand and in part published. 



This work has the general title of "Our present knowledge in regard to 

 the origin of Birds," and is published in Danish in The Journal of the Orni- 

 thological Society of Denmark (Copenliagen) . It is profusely illustrated by 

 drawings made by the author and selected from the works of other authori- 

 ties on the subject. Parts I and II have already appeared, the first in 

 Hsefte I and II, Vol. 7, Jan. 1913, and the second in Hsefte I and II, Vol. 

 8, Oct., 1913. There is an excellent introduction to these researches 

 in Part I, wherein the contributions of Liitken, Huxley, Balfour, and others 

 are quoted and compared. Chapter I is a classic in itself, for all the early 

 bird-forms are compared and beautifully figured, such as Archoeopteryx, 

 Hesperornis, Phororhacus, Pachyornis, and numerous others, full credit 

 being given to Marsh, Owen, Dames, Brehm, Sternberg, and others. 



Part II is a remarkable production, treating, as it does, of the "Resem- 

 blances between Aves and ancient or prehistoric Reptiles." The figures 

 are extremely interesting, and the labors of Cope, Cuvier, and many other 

 authorities are compared. In Section II of this chapter, wherein the 

 principal species of Dinosaurs are taken up, Mr. Heilmann gives us some 

 of his own very clever restorations, and the works of Dollo, Pycraft, and 

 many others are reviewed and compared in commendable detail. 



An almost unique feature of the work, as thus far pubUshed, is the 

 comparison of the modes of locomotion in birds and reptiles, existing and 

 extinct. Here the admirable studies of Saville Kent and others come into 

 play with striking examples to illustrate the author's views. Work of 

 Americans in these fields is used with good effect, as the contributions by 

 Schuchert, Lull, Eaton, Osborn, and' others. 



Mr. Heilmann intends to complete this work in five Parts; the next Part 

 (III) will be devoted to comparative embryology; Part IV, to the Anatomy 

 and Biology of Aves and Reptilia, and, finally. Part V, to a recapitulation 

 and summing up of conclusions. Mr. Heilmann has extended to me the 

 right to bring this work out in English; and should my time admit of it, 



