44 THE VOYAGE OF H.M.S. CHALLENGER. 



Its nature and relations in the group have subsequently been more extensively investi- 

 gated by Keinhardt (vide supra, p. 8), who calls it the " os crochn." 



When best developed, as in the Albatrosses, the "ossiculum lacrymo-palatinum " is a 

 small styliform ossicle of nearly cylindrical (as in Thalassiarche cidminata, PI. VI. fig. 7) 

 or somewhat lamellar (1'Iuihctria fuliginosa, PI. VI. fig. 8) shape, attached above by 

 an articulation to the inner face, of the descending limb of the lachrymal bone, and below 

 connected by a ligament to the upper surface of the palatine bone. Seen from the 

 side, in the dried skull (vide PL VI. fig. 1) the bone is visible below the malar arch. 

 It lies, in the recent state, in a cavity between the nose and the roof of the mouth, 

 in an oblique position, pointing downwards and inward. This bone is present in all 

 the genera and species of Albatrosses examined by me, as well as in Thalassiarche 

 chlororhyncha, as mentioned by Keinhardt, In the Oceanitidas, in Procellaria and 

 Cymochorea, as well as in Daption and Pagodroma, its place is taken by a narrow 

 ligament in which there is no ossification at all. In Bulweria, Peleca?ioides, Fulmarus, 

 Thalassceca, and Ossifraga there is a similar ligament, with a small, more or less ossified 

 nodule of bone lying in it, only connected by connective tissue with the surrounding 

 bones. In Aeipetes, Prion, Puffinus, Majaqucus, Adamastor, and (Estreldta it is small 

 and delicate, articulating with the lachrymal above, and ending freely (in the cleaned 

 skull) below. 



It is interesting to observe that a very similar bone, both as regards shape and 

 position, occurs in the genus Fregata as already pointed out by Eeinhardt, whose 

 observation I have been able to verify. But it also occurs in forms so different from 

 these as the Musophagidad, many Cuculida?, Chunga and Cariama, as well as in some 

 Laridse and Alcidaa, so that its presence is obviously of no particular taxonomic value. 

 Professor Parker informs me that its precise morphological significance is at present 

 rather uncertain. 



The palate (vide PI. VI. figs. 2 and 4) is always more or less incomplete below, 

 the fissure dividing it being, by the less degree of inward development of the maxillary 

 processes of the premaxilla?, and of approximation of the inward edges of the maxillo- 

 palatines and palatine bones, longer and wider in the smaller than in the larger 

 forms. 



The maxillo-palatine processes are concavo-convex lamella?, extensively fenestrated, 

 pointing backwards, and with their inner edges appearing but slightly internal to the 

 palatine bones. They remain free from each other in the middle line, and are also 

 unconnected by ossification with the vomer or nasal septum. Hence the Tubinares are 

 in this point strictly schizognathous birds. But in the Albatrosses, where the maxillo- 

 palatines are very large and nearly vertical in position, the sjiace between their inner 

 edges is very narrow, and just in front of them the decurved end of the vomer fills up 

 the intervening chink, especially in Phcebetria fuliginosa, where it is firmly fixed to, 



