THE VOYAGE OF THE ' CHALLENGER.' 



387 



fig. 7 represents those of Majaqueus slightly enlarged. They are usually 

 situated quite close to the cloaca, the large intestine in nearly all the 

 Tubinares being quite short ; the length of the caeca themselves rarely 

 exceeds '25 inch, except in the very largest species (vide table below). 

 In five specimens (one a nestling) of Cymochorea leucorrhoa that I have 

 examined, I find only a solitary caecum, lateral in position, developed, 

 owing apparently to the abortion of its fellow. As Mr. Swinhoe in his 

 description of Cymochorea monorhis * also records the caecum as single, 

 it is probable that the existence of such a single caacum is a character of 

 the genus Cymochorea. It is not unusual, I may observe, in a group of 

 birds in which the caeca are of small size, and probably of no physiological 

 importance, to find specimens or species with the normal number of caeca 

 reduced by one. I may give as instances Mergus albellus (cf. Hunter, 

 Observ. vol. ii. p. 325 ; and Garrod, Coll. Papers, p. 220) amongst the 

 Anseres, and Plotus anhinga (Garrod, 1. c. p. 345) amongst the Stegano- 

 podes, not to mention all the Ardeidse amongst the Herodiones. In 

 Halocyptena, in the only specimen yet examined, I could find no trace 

 of any caeca at all, so that the tendency to their disappearance already 

 observable in Cymochorea seems here to have progressed further still. 

 The intestines are not capacious, but the commencing duodenum may be 

 slightly dilated. 



The following are intestinal measurements : 



Zool. Ohall. 

 Exp. vol. iv. 

 pt. xL p. 23. 



* Ibis, 1867, p. 387. I have examined the type of this species, which is now in 

 Mr. Seebohm's collection, and find it to be a true Cymochorea. 



2o2 



