CHIONIS MINOR. 107 



space, limited below by the pubis aud above by the ischium. It is con- 

 verted during life into an oval foramen by a stout ischio-pubic ligament. 

 The ramus of the ischium runs downward and backward as a long fal- 

 cate process, flat, thin, and curved on the flat somewhat inward. The 

 pnMs is long, very slender, shaped lilie an italic /, and crosses the is- 

 chium externally to its ramus, extending 0.40 beyond it, curving inward 

 as it passes backward. Both ischium and pubis extend considerably 

 beyond the coccyx posteriorly^, and approximate each otlier, inclosing, 

 with ilium, an irregular, circular outlet, of which the sacro-pubic diam- 

 eter is 1.30 aud the iuter-ischiatic 1.10 inches. Internally the ilia are 

 deeply excavated opposite the sacrum for the kidneys, so that the 

 acetabular and ischiatic foramina pass out laterally from the cavity so 

 formed. Its roof is crossed by the sacral trabeculi38, and encroached 

 upon by the sacrum, somewhat like the ridge pole and lateral ties of the 

 roof of a house. This iliac cavity is limited anteriorly by the margin 

 of a ridge formed by the fusion of the ischium and pubes. Posteriorly, 

 althougli the rami of the ischium do not articulate or fuse together, 

 they touch, doubtless closing during life the whole ol)turator space, here 

 very long and narrow. 



STATExMENT OF CONCLUSIONS DEDUCED FROM THE FORE- 

 GOING. 



HABITS, GENERAL APPEARANCE IN LIFE, AND EXTERNAL CHARACTERS. 



The observer is first struck by the strong resemblance which CMonis. 

 bears to the pigeons, in general appearance, gait, and mode of flight. 

 The general shape of the body is of an ordinary columbine character, 

 the head being notably small, as usual in that group, the neck short 

 and full, and the body plump j the tail, moreover, having but 12 rectrices. 

 The sheath of the bill may furnish a distant analogy with the soft, 

 swollen membrane which covers the nostrils throughout the Columbce. 

 But this is a mere resemblance, the affinity indicated being, as will ba 

 seen later, with such sheaths as the Procellariidce and especially Lestri- 

 dincG bear. The strongly convex outline of the frontal feathers at the 

 base of the upper mandible is a very decided columbine feature. These 

 superficial resemblances to Columbce are not correlated with more impor- 

 tant structural characters, and are themselves overbalanced by other 

 external features, which indicate relationship with other groups. Thus, 

 the pterylosis is entirely different, large after-shafts and abundant dowu 



