256 CETACEA 
each side of the middle part of the upper jaw, but embedded by 
their roots only in the gum, and not in bony alveoli. This fact, 
with the frequent presence of rudimentary teeth in other species 
of this and the last genus in both upper and lower jaws, 
suggests the idea that the Ziphioids are derived from ancestral forms 
which had teeth of normal character in both jaws; the dentition 
of the living forms having become greatly specialised. The existing 
species of this genus are widely distributed in both northern and 
southern hemispheres, but most frequent in the latter. The best 
established are Jf. bidens, M. ewropeus, M. densirostris, M. layardi, 
M. gray, and M. hectori ; but there is still much to be learned with 
regard to their distinctive characters and geographical distribution. 
They were abundant in the Pliocene age, as attested by the fre- 
quency with which the most im- 
perishable and easily recognised 
portion of their structure, the 
long, cylindrical rostrum of the 
skull, of more than ivory dense- 
ness, is found among the rolled 
and water-worn fragments of 
animal remains which compose 
Fig. 87.—The left periotic bone of Meso. the well-known ‘bone-bed” at 
plodon; from the Red Crag of Suffolk. The 
smooth concave surface in the right upper the base of the Red Crag of Suf- 
corner of the figure forms the anterior ar- folk. Several species have been 
ticulation with the tympanic. (From the foynded upon the evidence of 
Cat. Foss. Mamm. Brit. Mus. pt. v. p. 70.) these rostra. Periotic bones of 
this genus (Fig. 87) are of less common occurrence in the Crag ; 
the figure is given to illustrate the characteristic features of this 
bone in the present family. 
Berardius.|—Two moderate-sized, compressed, pointed teeth on 
each side of the symphysis of the mandible, with their apices directed 
forwards, the anterior being the larger of the two and close to the 
apex. Upper ends of the premaxille nearly symmetrical, moder- 
ately elevated, very slightly expanded, and not curved forward over 
the nares. Nasals broad, massive, and rounded, of nearly equal 
size, forming the vertex of the skull, flattened in front, most 
prominent in the middle line. Anteorbital notch distinct. Rostrum 
long and narrow. Mesethmoid only partially ossified. Small 
rugous eminences on the outer edge of the upper surface of the 
maxillz at base of rostrum. Vertebrate: C 7, D 10,L 12,019; 
total 48. The three anterior cervicals ankylosed, the rest free and 
well developed. 
The only known species, B. arnua?, attains the length of 30 
feet, and has hitherto only been met with in the seas around New 
Zealand. 
1 Duvernoy, Ann. Sct. Nat.-Zoologic, sér. 3, vol. xv. p. 41 (1851). 
