THE VOYAGE OF THE ' CHALLENGER.' 383 



beak is fringed in a way similar to that here described is Halobwna 

 ccerulea, of which, however, as yet I have been unable to examine more 

 than skins. 



The existence of a peculiar fringe of lamellae along the margin of the 

 mouth has often been insisted on as an argument for placing Phoenicopterus 

 amongst the Lamellirostres ; but the development of, at least, a very 

 similar arrangement in Priori and Halobcena, birds of a very different 

 group again, ought to show that an adaptive contrivance of this kind 

 may be, apparently, independently developed without great difficulty, and 

 yet with many features of common resemblance, in different birds 

 without necessitating any immediate genetic connection between its 

 possessors. 



In Falmarus (PI. XIY. fig. 4) a rudimentary fringe of the upper 

 mandible is present, a little more developed than in Daption ; in other 

 respects it conforms to the type of GEstrelata, the spines, however, being 

 very small and rudimentary. Ossifraga is similar in all essential points, 

 but the palate is longer, and, at least in young birds, more spinulose. In 

 Aeipetes and Thalassoeca the pectination of the mandible can only just be 

 traced; the palate is much longer and narrower in shape than in 

 Fulmarus, the spines smaller, and the palatine ridges better marked. 



In Pelecanoides (PL XIV. fig. 2) the palate is quite smooth throughout, 

 with no ridges or spines, except on the area round the posterior nares, 

 which is pretty uniformly covered with sharp elongated spines of fair size. 

 In the Diomedeinse the palate is comparatively smooth. There is a 

 long prenarial ridge, only with slight indications of spines at its most 

 posterior part. The spines bounding the narial and Eustachian apertures 

 are well-marked, those on the palate small and best developed towards 

 the posterior end of the prominent palatine ridges. Between the latter 

 and the median fissure are developed, especially in Diomedea exulans, 

 additional spines of small size, as well as a short row outside their most 

 posterior part. Outside the tongue, between it and the inner margin of 

 the jaws, the mucous membrane of the floor of the mouth has on each 

 side a well-developed series of stronger spines. 



The tongue, as may be seen by a glance at Plate XV., where the chief 

 variations of its form are represented, is by no means constant in shape 

 in the Tubinares. 



In the Oceanitidae (vide PI. XV. fig. 1, Oceanites), and the genera 

 Cymochorea (fig. 5), Procellaria, and Halocyptena of the Procellariidae, the 

 tongue is of triangular shape, fairly fleshy basally, but tapering and 

 becoming thinner anteriorly, its extremity being pointed and more or less 

 membranous, so as to easily be destroyed by rough usage. Its posterior 

 margin, or base, is somewhat concave, and fringed by a row of small 

 retroverted pointed papillaB. This is the form of tongue found, more or 

 less modified, through the entire group. 



