AND DEVELOPMENT OF THE BIRD'S SKULL. 123 



missure, and the medio-palatine, which occurs there, is azygous. The median septo- 

 maxillary turns up again in the Woodpecker ; it has been already described in the 

 Humming-bird (Plate XXII. figs. 3 & 4, smx') ; it exists free in the Coracomorphous 

 genus Homorus, and ankylosed to the vomer in Gymnorhina. For a vomer like the 

 one figured here (fig. 4, v) we must look to some Celebesian Passerines. I have it in 

 Nectarophilus Grayi and in Anthreptes malaccensis ; especially characteristic is that of 

 the former *. 



But the vomer in these Passerines is confluent by its forks with the inturned alinasal 

 wall ; in Megalcema the arms of the Y form a neat joint, apparently without a cavity 

 (Plate XXIII. fig. 4, v, mxp), with the corresponding maxillo-palatine plates. The nearest 

 relation of this type known to me at present is the Roller ( Coracias garrula) : this is one 

 of Cuvier's " Passerines ;" but it is far less passerine than Megalcema, and has a chelonian 

 azygous vomer. The narrowish, parallel, neat palatines are very much like those of the 

 Poller, but they are narrower, have a less distinct inner keel, and have distinct interpalatine 

 processes (ipa) ; the rudimentary transpalatine angle (tpa) is nearly equal in the two 

 kinds. The large mesopterygoid (fig. 5, mspg) is semidistinct, and has not united with the 

 palatines in this specimen. In Coracias these parts are quite passerine, the mesopterygoid 

 having united with the palatine on one side, the left, whilst on the other all these are 

 fused together. In Coracias the epipterygoid process is abortively developed ; in 

 Megalcema (fig. 4, epg) it is an elegant rounded lobe. In Coracias the maxillo-palatines 

 are large, and have a complete ankylosis with each other ; in Megalcema (fig. 4, mxp) 

 they are smaller and do not meet, being kept apart by the " median septo-maxillary " 

 {smx'). 



In Coracias the lacrymal has its largest development and the ecto-ethmoid the least ; 

 in Megalcema these things are reversed, and the lacrymal (fig. 5, I) is a mere point, 

 whilst the ecto-etbmoids(e£^,j?p) are like those of the Passerines and Hemipods, being 

 largely exposed in the frontal region. In the structure of the nostrils the two types 

 agree ; but conformably with its more intensely cuculine character, the Poller has a 

 very massive, spongy, osseous nasal septum ; it also has very large but non-functional basi- 

 pterygoids. 



The characteristic modifications of Coracias are exaggerated in Burystomus, save that 

 its basipterygoids are aborted. In no Owls that I have seen does the bone become so 

 frail a sponge as in the enormous lacrymals of that type ; the ecto-ethmoids are in it 

 very minute flaps, the outer part of which is not ossified, as in Caprimulgus. Eurystomus 

 is a Poller, making no inconsiderable approaches to the Owl-like nocturnal Ouculines 

 next to be noticed. 



The first of these is the Guacharo, or " Oil-bird" (Steatomis caripensis, Humb. ; 

 Podargus, Ouv., Temm.). 



The high arch both of beak and skull makes this bird's head most completely iso- 

 morphic of that of the Owl ; its basipterygoids are well developed (of enormous breadth, 

 the articular facet being oblong rather than oval), thus agreeing with the Owl and Fern- 



* The figures and descriptions of these forms, and of many others referred to in this paper, will soon appear in 

 the ' Zoological Transactions.' 



SECOND SERIES. — ZOOLOGY, VOL. I. S 



