STEGANOPODES 



403 



The tufted oil gland has four orifices in Phalacrocorax 

 brasiliensis and in Plotus melanog aster. Phaeton has six, 

 the other genera apparently two, save Pelecanus. which has 

 the unusually large number of twelve. 



The pterylosis, on the other hand, is very uniform, and 

 the feathering is very close. The neck and head are closely 

 feathered, and there is a very narrow apterion on the breast. 

 The spinal tract has a very limited apterion between the 

 shoulder blades. 



The tongue is small in this group, practically obsolete in 

 Plotus (see fig. 5, p. 20) . The proventricular glands are in two 

 large squarish patches in Phalacrocorax (brasiliensis) . The 

 remarkable modifications of these organs in Plotus are 

 described later (p. 414.) 



The gizzard is very small in Pelecanus and Sula, thfe 

 proventriculus being enormous. The glands are zonary in 

 arrangement. 



The following are measurements of the alimentary tract 

 in a series of Steganopodes. The most remarkable fact to be 

 noted in the table is the great length of the large intestine 

 in Plotus. 



* These measurements are derived from deseriptwns. 



The varying proportions of the liver lobes ^ are given in 



St. Petersburg, 1840, p. 239 and pi. v., and in a paper by myself, P. Z. S 

 1897, p. 288. 



' G. Alix, ' Sur I'Anatomie du Pelican,' Bull. Soc. Zool. Fr. ii. 1877, p. 



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