94 Correspondence. I'f™ 



work, is by no means small. Furthermore, the investigations in avian 

 anatomy since 1840 have so changed our ideas of the classification of 

 birds, new and important truths may perhaps be learned from work which 

 he has already done. The enormous increase in the number of known 

 species since that time is another and good reason for believing that new 

 and important facts remain to be discovered in this interesting field. 



Since then it is evident that much might be added to the work which 

 Nitzsch has done, the feeling that the subject is of such very slight im- 

 portance is probably the real cause for its neglect, but careful thought will 

 show that this is a serious blunder, for no investigation in nature can be 

 unimportant if it is conscientiously and zealously worked out, and the 

 number of problems to be solved is at least as great in pterylography as 

 in many more popular branches. The relations between the distribution 

 of pterylae and the mode of life, or the speed of flight, or the protection of 

 the body, or even the kind of food, have as yet been scarcely thought of, 

 while the relative advance in spacial distribution from what are called the 

 lower, to the higher forms may bring out new facts in the history of evo- 

 lution. The generic, specific, and even sexual differences which may be 

 found, require investigation and explanation, and these are only a few of 

 the questions involved. But so little has yet been done in America that 

 the mere recording in descriptions and figures of our thousand species 

 will furnish ample occupation for a number of years yet. Thus it will be 

 readily seen that this field of study, so sadly neglected in the past, espe- 

 cially invites the attention of scientists today. American ornithologists 

 have had so much to do in making known the avifauna of our own 

 country that they have a good excuse for having neglected the study of 

 pterylography, but now at least the time has come when they should enter 

 in and possess the field. 



Dr. R. W. Shufeldt has already done some very interesting work in this 

 line, and it was an article of his, published in 'The Auk' about three j'ears 

 ago on the pterylosis of certain western Pici which first awakened my in- 

 terest in the subject. A perusal of Nitzsch's great work, together with 

 some investigations of my own, aroused my enthusiasm over what seems 

 to me a fascinating field for research, and the scarcity of literature on the 

 subject has led me to make this appeal for an apparently neglected branch 

 of ornithology. 



Hubert Lyman Clark. 



Pittsburg, Pa., Dec. 13, 18Q2. 



[Mr. Clark's letter calls attention to a most interesting and important 

 field for research, in which as yet very little systematic work has been 

 done, the subject proper remaining nearly where Nitzsch left it half 

 a century ago. Many years since the present writer had the good fortune 

 to become a student of zoology under the late Prof. Louis Agassiz at 

 Cambridge, Mass., with a view to special work in ornithology. The first 

 subject to which my. attention was invited was the structure and distribu- 

 tion of feathers, and the classic work of Nitzsch was soon placed in my 



