1868.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 175 



This character can, however, be of but little value, since the process 

 varies in shape even among species very nearly related. Mimus baha- 

 mensis, for example, differs from its near relations in having a blunt 

 transpalatine very much like Turdus mustelinus. 



The Wrens, however, agree among themselves in possessing a trans- 

 palatine process terminating in a sharp point of the pattern indicated 

 in Plate xxxvn, fig. 1. 



Passing to the maxillo-palatines we find these little processes to have 

 the same shape in Mimus, Mimodes, Harporhynclius, Melanoptila, and 

 Oreoscoptes. This last-named bird I have not examined, but Dr. Shu- 

 feldt's description agrees exactly with that of the corresponding process 

 in the other species above mentioned.* 



Galeoscoptes differs from the other Mimince in the shape of the maxillo- 

 palatines, which conform very nearly in pattern to those of the Thrushes, 

 who agree among themselves in having the maxillo-palatines of the 

 shape shown in Plate xxxvir, Fig. 3. 



The Wrens have a very characteristic, slender, and sharply-pointed 

 maxillo palatine, the shape of which can best be understood by a refer- 

 ence to Plate xxxvn, Fig. 1 . 



In spite of the fact that Galeoscoptes does not agree with the other 

 Mimince in the shape of its maxillo palatines 1 am inclined to place 

 considerable taxonomic value on this process for the distinguishing of 

 nearly related forms, especially when correlated with other characters. 



This surmise should, however, be tested by the examination of a large 

 series of specimens, but in addition to the species noted in this paper I 

 have found that our six species of Swallows have each and all the same 

 shaped maxillo palatine, while Micropus apus, M. melanoleucus, M. sub- 

 fureatus, Chceturapeiasgia, Collocalia fucipliaga, and Dendrochelidon mys- 

 tacea also have their own characteristic-maxillo palatine. 



The anterior extremity of the vomer is subject to great specific vari- 

 ation of form, and I have been unable to find that it has, if any, more 

 than an extremely slight taxouomic value. 



The shape of* the tympanic fossa is even more variable, but the tem- 

 poral fossa seems to present more tangible characters. 



Thus in the Thrushes this fossa is so deep and produced so far back- 

 ward as to make a very noticeable notch in the contour of the skull 

 "when viewed from behind. This notch was least marked in Turdus 

 musicus, possibly from the fact that the specimen examined had been a 

 cage bird. In the Mimince, and also in the Wrens, the temporal fossa is 

 shallow and not produced backward, thus breaking in but little on the 

 transverse outline of the cranium. 



The form of the scapula is so extremely variable that it can furnish 

 at the best specific characters only. As a rule it is more decurved and 



* Since this was written Dr. Shnfeldt has kindly sent me two specimens of Oreos- 

 coptes, which show that the maxillo-palatines have the same shape as those of Mimus, 

 etc. 



