MR. W. H. FLOWER ON THE OSTEOLOGY OF THE SPERM-WHALE. d49 
PLATANISTID!. 
li oe Cn25=ols 
Ler enis=41. 
DF TOS Eee Cis =42: 
Platanista gangetica (Eschricht), C. 7, D. 
Inia geoffrensis (Brit. Mus.), C. 7, D. 13, 
Pontoporia blainvillii (Burmeister), C. 7, 
DELPHINIDE. 
Beluga leucas (Mus. Louvain), C. 7, D. 10, L. C. 33=50. 
Monodon monoceros (Mus. Roy. Coll. Surg.), C. 7, D. 11, L. 6, C. 26=50. 
Phocena communis (Mus. Leyden), C. 7, D. 13, L. 14, C. 30=64. 
P. communis (Mus. Roy. Coll. Surg.), C. 7, D. 13, L. 14, C. 30=64. 
P. communis § (Mus. Roy. Coll. Surg.), C. 7, D. 13, L. 14, C. 32=66. 
P. communis 3 (Mus. Oxford), C. 7, D. 12, L. C. 46=65. 
Neomeris phocenoides (Mus. Leyden), C. 7, D. 13, L. 13, C. 30=63. 
Orca gladiator (Mus. Leyden), C. 7, D. 11, L. 10, C. 23=51. 
O. gladiator (Mus. Cambridge), C. 7, D. 12, L. C. 33=52. 
Pseudorca crassidens (Reinhardt), C. 7, D. 10, L. 9, C. 24=50. 
Globiocephalus melas (Mus. ea Coll. Surg.), C. 7, D. 11, L. 12, C. 28=58, 
G. melas (Middlesex Hosp.), C. 7, D. 11, L. 13, C. ei Biac 
G. ? (Tasmania, Mus. Roy. i Surg.), C. 7, D. ; E 
Delphinus sinensis (Mus. Roy. Coll. Surg.), C. 7, D. 12 i tOs C22; 
D. guianensis (Van Beneden), C. 7, D. 12, L. 14, C. 22= 
L. 17, C. 25 
13, L. 15, C. 30=65. 
9: 9 
D. heavisidii (Mus. Leyden), C. 7, D. 
D. superciliosus (Mus. Leyden), C. 7, D. 13, L. 
D. delphis (Mus. Roy. Coll. Surg.), C. 7, D. 13, L. 2, 
Lagenorhynchus leucopleurus (Mus. Leyden), C. 7, D. 
L. albirostris (Mus. Cambridge), C. 7, D. 14, L. C. 6 pas 
It will be seen from this Table that the total number of vertebra varies extremely 
in different genera, and even in species of some natural genera, the variation being 
chiefly in the lumbar and caudal regions. The well-marked group Physeteride, com- 
prising the five genera placed at the head of the list, are all characterized by rather a 
small number of vertebree; but among the other families there are many which have 
quite as few as some of the former. For instance, the vertebral formule of Platanista, 
Beluga, Monodon, and Orca closely resemble that of Physeter. It is singular that the 
most nearly allied genus, Aogia, differs so much in the number of dorsal vertebre. On 
the whole, little reliance can be placed on these numbers for classificatory purposes, 
as shown by the extraordinary excess to which they run in Lagenorhynchus, a torm 
otherwise not possessing any special modification. 
The characters of the cervical region of the genus Physeter have already been shown 
to be quite peculiar to itself. The dorsal region presents a remarkable disposition of 
VOL. VI.—PART VI. 3c 
D. tursio (Mus. Leyden), C. 7, D. 13, 
vy 
