226 PEOFESSOE FLOWER ON THE EECENT ZIPHIOID WHALES. 



The neural arches thus differ greatly from those of Hyperoodon, which has one tall 

 conical upright spine springing from the conjoined arches of the six anterior vertebrae, 

 and a second slender but equally elevated and vertical spine, belonging to the seventh 

 vertebra alone. On the other hand they resemble generally those of Ziphius and 

 Mesoplodon, as far as their condition in these genera is at present known; for the 

 incompleteness of the upper part of the arch exists in the fourth and fifth vertebra? in 

 Ziphius australis, and in the third, fourth, and fifth in Mesoplodon soiverbyi. Perhaps 

 even more strikingly does the presence of well-developed inferior transverse processes 

 to the third, fourth, fifth, and sixth cervical vertebra? show the affinity of Berardius to 

 these two genera and its dissimilarity to Hyperoodon. 



Dimensions of the Cervical Vertebrce. 



inches. 

 Antero-posterior length of bodies of all seven, lower surface . . .10 



Length of body of united first, second, and third 3*6 



Length of body of fourth 1-4 



Length of body of fifth 1-4 



Length of body of sixth 1*5 



Length of body of seventh 1-8 



Height from top of spine to lower edge of body of second . . . 10*7 



Height from top of spine to lower edge of body of seventh . . . 8 - 5 



Breadth between outer borders of articular surfaces of atlas . . . 8 - 7 



Height of articular surfaces of atlas 5*8 



Breadth between tips of transverse processes of atlas 11*5 



Height of neural canal in arch of atlas ,.. 2*9 



Greatest breadth of neural canal in arch of atlas 3-3 



Height of neural canal in arch of seventh 3 - 3 



Greatest breadth of neural canal in arch of seventh 3*6 



Breadth of body of seventh 5-2 



Height of body of seventh 4*2 



Breadth between tips of transverse processes of seventh .... 9-5 



Thoracic Vertebrce. — The bodies of the twelve thoracic vertebra? increase gradually in 

 length (see table on p. 228, and PI. XXVIII. fig. 1). The inferior surface of those at 

 the commencement of this region is broad, flat, and somewhat rough ; posteriorly they 

 gradually acquire a median keel. 



The spines are moderately high, compressed, sloping much backwards ; that of the 

 first is very little developed, and pointed ; though tapering in the anterior vertebra?, 

 they gradually become more obtuse and truncated at the extremity as they approach the 

 posterior end of the series. 



The zygapophyses are unusually well developed, continuing on the contiguous anterior 



