14 BULLETIN" 50, UNITED, STATES NATIONAL MUSEUM. 



treatment! It ma}' be, and doubtless is, perfectly true that no more 

 than threo Passeriform groups can be defined which will be equal in 

 taxonomio rank to the families of other orders of birds; but the objection 

 to this meager allowance — and it is a Verj' serious one — is that two of 

 the three groups contain together only about one-fifth the total num- 

 ber of species, so that there are still left about five thousand species in 

 the third. Obviously, these five thousand species (more or less) must 

 be susceptible of segregation into a considera))le number of more or 

 less trenchant groups; and there being so few grades of rank between 

 a family and a genus, what to call these groups becomes a verj' serious 

 question. The ordinary terminology of zoology evidently will not 

 sufiice; and if no more than three families of Passeriformes are recog- 

 nized, a new and complicated nomenclature for the intermediate groups 

 becomes necessary. 



As a provisional expedient, I propose to call the Passerine ''families" 

 of Gadow ^' svperf(t)nil-ies,''' and retain the former term for such groups 

 of genera as can be trenchantly separated from all others. Whether 

 this action will necessitate a reduction or an increase in the number of 

 so-called families over that generallj^ accepted can only be determined 

 after careful and thorough studj^ of the entire order. This is a task 

 for which the author of this work is unprepared, either as to time or 

 material. The best that he can do here is to limit investigation in this 

 direction to the American forms. Of course the result of such limited 

 research can not be entirely satisfactory; but it may serve to show, 

 perhaps more clearly than has been done before, which currently recog- 

 nized families can and which can not be characterized. Nothing is 

 more certain than that the commonly accepted limits of some of the 

 so-called families of the Superfamily Oscines are purely artificial and 

 arbitrary. On the other hand, it is equally obvious that some groups 

 to which family rank seems due have been ignored or overlooked. 

 Until more is known concerning the internal structure of various forms 

 any classification of the Oscines mu^t be considered imperfect and 

 provisional. 



KEY TO THE SUBOKDERS OF PASSEKIFORMES. 



a. Hallux weak; feet syndactyle,^ the deep plantar tendons of Type I^ (desmopel- 



mous'); cervical vertebree 15; spina externa eterni long, simple Desmodaotyli. 



aa. Hallux the strongest toe; feet eleutherodactyle,^ the deep plantar tendons of Type 

 VII^ (schizopelmous^); cervical vertebras 14; spina externa sterni short, 

 forked Eleutherodactyli. 



^In the syndactyle or desmopelmous foot the flexor perforans digitorum and flexor 

 halluds longus tendons are united at their crossing point by a vinculum. In the 

 eleutherodactyle or schizopelmous foot, on the other hand, these tendons are quite 

 separated from one another. 



''Gakrod, Proc. Zool. Soc. Lond., 1875, pp. 339-348; Gadow, in Bronn's Thier- 

 Eeichs, Vog., 1891, p. 195, ii, Systematischer Theil, 1893, pp. 224, 225; in Newton's 

 Dictionary of Birds, pp. 615-618. 



