NATURAL SCIENCES OF PHILADELPniA. 173 



with the inner anterior digit, which defines what we now recognize as the tribe 

 or rather suborder Totipalmi, embracing numerous families. Proceeding upon 

 this basis we should be obliged in like manner to form a tribe or suborder 

 " Linearinares " of what is now known as the family Laridiv, and erect its four 

 recognized subfamilies into as many families. 



Hy Bonaparte* the order Gaviag is made to consist of two tribes, the Toti- 

 palmi eiud the Longipcninv ; the latter containing two families, — Laridx a.n& 

 I'rocellariidii: — the differences between which essentially rest in the linear or 

 tubular form of the nostrils; for continuity or division of the corneous rostral 

 envelope does not always point to one or the other family, as the Lcslridinx of 

 the Laridoi have somewhat the features of the Procellariidce in this respect. In 

 this arrangement an essentially brachypterous bird, — one truly a "diver" 

 rather than a "flyer " in the sense in which these words are technically ap- 

 posed — is classed among the Lougipennines. 



If a tubular rhinotheca be really the most essential feature, and at the same 

 time of no more than family value, then its modifications may with propriety be 

 held as indicative of three subfamilies iJiomedcinie, rrocellariincB, and Ilalodro- 

 miuiK. Bui it is questionable whether such be indeed the case. An approach 

 to this feature is seen in the Lestridinic, (of a family otherwise exhibiting 

 strictly linear basal nostrils, and an undivided rhynchotheca ;) in which the 

 so-called "cere" is really a segmentation of the corneous envelope and pro- 

 bably also indicative of tubulalion of the nares. It is by no means proven 

 that the peculiar nostrils of the rrocellanidie as generally defined, should not 

 be held as subsidiary in importance to, or at least of no more than coordinate 

 v:ilue with, other points of structure. Upon such an hypothesis the birds now 

 Called Pro cellar iidx would be divisible into three families, somewhat accord- 

 ing to the following schedule : — 



I. Tridactyle. 



A. Maciopterous ; "flyers;" the tubular nostrils disjoined, 



lateral, horizontal Diomedeidm. 



B. Brachypterous; "divers;" the tubular nostrils united, 



culminal, vertical Halodromidce. 



II. Tetrad actyle. 



Macropterous ; " flyers ; " the tubular nostrils united, cul- 

 minal, horizontal Procellariidx. 



But this arrangement is as faulty as the otliers, in the presence of an incon- 

 gruous brachypterous element; and we should moreover be obliged to recog- 

 uize a tribe or suborder for the three families thus collocated. 



It will be evident, therefore, that so long as we regard a tubular rhinotheca 

 as a primary fundamental character, not permitting of a wide separation of the 

 forms in vihich it is present, we shall bring into juxtaposition certain types 

 widely dissimilar from each other in most other respects ; and that we do not 

 obviate this difficulty when we make this character indicative of a suborder, 

 under which several families may be ranged, any more than in considering it 

 as of family importance, and forming our subfamilies upon its modifications. 

 In either cf.se we are met by the same objection. It remains to be proven that 

 tubulation of the external nares is not a feature of subordinate importance to 

 others, and as such, one which may cccxist in types otherwise presenting a 

 widely diverse assemblage of characters. In which event, at least one genus 

 now held as Procellaridian will be found to constitute a family of quite a dif- 

 ferent suborder ; and certain others will form at least a family distinct from 

 that of the Petrels proper. The test of anatomical investigation must be ap- 

 plied before the question can be definitely settled ; for iu one sense external 

 characters of every sort are but the indices, as it were, of fundamental struc- 



• Schema Systcmatis OrnithologiaB, Compt. Rend, xxxyii. 1853. 



1866.] 



