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



of the British Museum. 1 The crania have characters which distinguish them from the 

 other genera of the same family and which approach in some degree to the characters of 

 Cystophora, so that Ommatophoca is a well-marked genus. It approximates to Cysto- 

 phora in the vertical direction of the anterior nares, in their relation to the infraorbital 

 foramina, and in the shortness of the ascending part of the premaxilla, so that a definite 

 part of the anterior nares is bounded by the superior maxilla. In the great width of the 

 orbits and of the skull in the interzygomatic region they also approach each other. On 

 the other hand the nasals are much longer in Ommatophoca than in Cystophora, and 

 the superior maxillae articulate with their outer border as far as the tip, and do not leave 

 the anterior part of this border free ; the palate plates of the palate bones are much 

 shorter in Ommatophoca than in Cystophora, and they differ from each other in the 

 number of lower incisors and in the shape of the crowns of the post-canine teeth. 



Monachus, Fleming. 2 



Premaxilla articulating with side of nasal ; anterior nares oblique and a short distance 

 in front of the infraorbital foramina ; no postorbital process. Nasals not greatly elongated. 

 Inner wall of orbit defective ; zygomata expanded and the width greater than cranial 

 width. Hard palate slightly emarginate, the posterior border considerably behind 

 maxillary root of zygoma and some distance in front of the hamulars, which are rudi- 

 mentary, and well in front of the anterior border of the glenoid fossae ; the posterior 

 border of vomer just visible in palatal cleft, and arching forwards to join vomerine crest 

 about junction of superior maxilla and palate. Pterygoids everted and running almost 

 horizontally forwards, with large foramen between the upper border and the basis 

 cranii ; the interpterygoid width considerable. Tympanic bulla swollen, scarcely ridged, 

 apex truncated ; basi-occipital perforated mesially ; mastoid low ; par-occipital prominent ; 



.2-2 1-1 5-5 



occipital condyles confluent. Dentition — in. .y—?, c. ^ _} , p. c. g_g = 32. 



1 The description of Ommatophoca and Monachus has been written from the crania in this Museum, and I am 

 indebted to Professor W. H. Flower, C.B., for permission to examine these and other crania of the Seals in the national 

 collection. 



2 The generic name Monachus was suggested by Dr. Fleming in 1822. In a footnote to his Philosophy of Zoology, 

 vol. i. p. 187, he says, " Some Seals as Phoca monachus are said to have four incisors in each jaw. Such will probably be 

 constituted into a new genus under the title Monachus." In 1827, F. Cuvier used the name Pelagios {Mem. Mus. Hist. 

 Nat., t. xi. p. 196), and in 1829 (Diet. d. Sci. Nat., t. lix.) Pelagius, but Fleming's name has obtained general use for this 

 Mediterranean Seal. 



