STTJDIES OF THE MACEOCHIEES. 



391 



of another form which may happen to possess an unnotched 

 sternum, it means nothing so far as affinity is concerned. This 

 becomes the more evident when the sterna themselves are 

 fashioned upon essentially different plans, as is the case in the 

 Cypseli and Trochili. 



Truly related organizations never exhibit such an array of in- 

 harmoniously associated sets of morphological characters. And 

 it is to the detriment of comparative anatomy, and all we may hope 

 to effect by it, to summon to our aid such characters as " short- 

 ness " (in the case of the humeri), as " presence " or " absence " of 

 parts (as intestinal caecae), and other matters of purely physical or 

 arithmetical interest, unless there can be shown in connection 

 therewith actual similarity in form and arraagement of parts. 



Now in my first memoir (Proc. Zool. Soc. 1885) upon this 

 subject, I proposed that in the Passeres the Cypseli should be 

 placed next to the Hirundinidce ; for convinced, as I was, of their 

 relationship, I for the moment did not take into account the 

 artificial boundary lines of orders, genera, and what not, demanded 

 on the part of systematists, simply having in my mind (after 

 working many weeks over their several structures) their affinities, 

 and not how they really ought to figure in print. 



Evidently this will not do, and we must assign them some 

 position in the system which they can occupy with propriety in 

 ornithological works, even if it does a little violence to the delicate 

 and intricate kinships, which the morphologist can so often see 

 with his mind's eye, but which sometimes look so startling in 

 type. 



There is but one way at present open to us to effect this, and 

 that is, all the true Swifts in the world must have a group or an 

 order created for them, as the order Cypseli, which I now pro- 

 pose for their reception. This Order, were it represented by a 

 circle, would be found just outside the enormous Passerine circle, 

 but tangent to a point in its periphery opposite the Swallows, 

 which latter are to be found just over the line of the arc. 



Eor the Trochili I have already proposed a separate order in 

 a former communication, and am to-day more convinced than 

 ever of the correctness of that proposal. 



The time may arrive when we shall see more clearly the rela- 

 tionship to other groups of birds of these markedly modified and 

 highly interesting little forms, but in the meantime a very great 

 amount of painstaking dissections upon avian types will have 

 to be successfully undertaken. Agreeing with the Psittaci in this 



