1874.] 



ANATOMY OF THE COLUMB.E. 



257 



ossification in the Nicobar Pigeon (Calcenas nicobarica) has already 

 attracted attention*. In Carpophaga the stomach is very feebly- 

 muscular, not being more powerful than in strictly fruit-eating birds, 

 such as the Hornbills. It is in the genus Ptilonopus that a form 

 of gizzard is developed such as is not found in any other bird. In 

 P. marice, P. melanocephalus, and P.jambu it is exactly the same, 

 being composed of four pads instead of two. A horizontal section 

 of an ordinary gizzard presents the well-known section represented in 

 fig. 2, b, it being composed of two muscular masses, which push the two 

 pads together in a manner which I have explained elsewhere f . But 

 hi Ptilonopus the section is much more elaborate, in a direction to 

 which no other gizzard is known to approach ; so that by the gizzard 

 alone the genus whence it came could be determined with certainty. 

 The accompanying figure (a) represents the section made exactly in the 



Fig. 2. 



Horizontal section of the gizzard of: — a. Ptilonopus jambu ; b. Treron calva. 



same direction as in the former case ; and from it the four longi- 

 tudinal muscular masses, which are here seen cut across, are well 

 displayed, leaving a cruciform cavity between them, through which 

 the food passes whilst being triturated. This gizzard is small in 

 proportion to the size of the bird. No approach to a like condition 

 is to be observed in Treron, the section of the gizzard in that genus 

 being quite of the ordinary form figured above. 



It is generally said that the gall-bladder is absent in the Columbae ; 

 and this is so in most of them ; but besides being developed in the 

 Pteroclidse, it is found in all the species of Ptilonopus, Lopholcemus, 

 and Carpophaga, In this point also Ptilonopus therefore differs 

 from Treron. 



The following Table contains the names of the different genera of 

 the Columbse arranged in the manner suggested above. As a classi- 

 fication of the suborder it is not at all my desire to put it forward as 

 an ultimate one, but simply as the expression of the known facts of 



* See Prof. Flower's observations, P. Z. S. 1SG0, p. 333, and Mr. Bartlett's 

 note, ib. p. 99. 

 t P. Z. S. 1872, p. 525. 



