May 13, 1887.] 



SCIEJSrCE. 



461 



occupying the position of a metacarpal, must be con- 

 sidered as its degenerate, representative, even if not 

 articulating with the carpus or metacarpus by means 

 of an arthrodial facet. This assumption woiild seem 

 to be borne out by such cases as those of the telemeta- 

 carpal deer, in which the distal portions alone of the 

 second and fifth metacarpals are present, and there is 

 no articulation whatever with the cannon bone. 



Would it not also be equally correct to deny the 

 right of the ' spurious hoofs ' in bison to be called 

 phalanges because they have no connection what- 

 ever with the metacarpals ? 



Now, in Bison americanus there is in every ' rough 

 skeleton ' examined a bone about ten millimetres in 

 length, occupying the place of the second metacar- 

 pal. Although this bone very rarely exhibits the 

 slightest trace of an arthrodial facet, it is neverthe- 

 less, from my stand-point, to be considered as a 

 rudimentary metacarpal. If not a metacarpal, what 

 is it ? In two skeletons out of six, there is a small 

 facet on one leg only, but the little bone above 

 mentioned is the bony core of a symmetrically shaped 



The maxillo-palatines of Tachycineta. 



The person who ' found fault ' with Dr. Shufeldt's 

 figure of Tachycineta thalassina (see Science, ix. No. 

 221) would like to say a few words by way of ex- 

 planation. I regret that my remarks should have 

 been construed as mere fault-finding. Nothing was 

 further from my intentions, and I should be extremely 

 sorry to have requited the many courtesies received 

 at the hands of Dr. Shufeldt in any such manner. 

 The shape of the maxillo-palatines of Tachycineta 

 constituted one of the links in the chain of Dr. 

 Shufeldt's argument ; and, as my own conclusions 

 in the subject under discussion were quite different 

 from his, it was needful for me to point out any 

 flaws, either of text or figure, which had a bearing 

 on the subject. While, at the time of writing the 

 ' Afl&nities of Chaetura,' there was no specimen of 

 T. thalassina at my disposal, I did have many speci- 

 mens representing every other species of North 

 American swallow. All of these agreed with one 

 another in the shape of the maxillo-j)alatines, and 



nixp 



Fig. 1. 



Fig. 2. 



Fig. 3. 



cartilaginous mass verj'^ like the better-developed 

 fifth metacarpal. 



Examination of the skeleton of aurochs in the 

 U.S. national museum shows that the facets for the 

 articulation of the fifth metacarpal are much larger 

 and more sharply defined than are those for the 

 articulation of the second. 



Owen notes that the genus Bison has two small 

 metacarpals, and it would seem safe to assume that 

 this is the normal number, the Cambridge skeleton 

 being in this respect abnormal. 



The deductions that I would make are these : -— 



1. Bison bonasus possesses two rudimentary meta- 

 carpals, both of which articulate with the common 

 bone by arthrodial facets. 



2. Bison americanus possesses two rudimentary 

 metacarpals, but the outer one alone regularly artic- 

 ulates with the cannon bone. 



To Dr. Slade, however, belongs the credit of point- 

 ing out that in this respect the American and Euro- 

 pean bison are different, and that the American is just 

 a shade more modified. FIiedekio A. Lucas. 



Washington, D.C., April 29. 



differed in toto with those of the skull figured by Dr. 

 Shufeldt. On the strength of these facts, I ventured 

 to state that the figure was imperfect in this par- 

 ticular ; and a skull of T. thalassina since procured 

 has the maxillo-palatines like those of its relatives. 

 Of the accompanying figures, fig. 1 is a tracing of Dr. 

 Shufeldt's figure in the Proceedings of the zoological 

 society, fig. 2 is the same figure with the maxillo- 

 palatines drawn from a specimen in the national 

 museum, while fig. 3 represents the palate of the 

 purple martin (Progne subis), which shows the 

 characteristic form of the Maxillo-palatines in the 

 swallows. Fig. 2 is not quite so good as I would like, 

 but there is no time to make a better figure. In the 

 examination of scores of crania, representing many 

 species of birds, I have never met with a single case 

 of individual variation of the maxillo-palatine pro- 

 cess, to say nothing of so great a departure from the 

 specific type as that indicated in Dr. Shufeldt's 

 figure. In fact, the shape of this process has been 

 found very constant in closely allied species, all 

 the thrushes examined having one pattern, the wrens 

 another, and so on. This being the case, it would 



