ME. W. H. TLOWEE ON THE OSTEOLOGY OP THE SPERM-WHALE. 349 



Platanistid^. 



Platanista gangetica (Eschricht), C. 7, D. 11, L. 8, C. 25^51. 

 Inia geoffrensis (Brit. Mus.), C. 7, D. 13, L. 3, C. 18 = 41. 

 Pontojooria blainvillii (Burmeister), C. 7, D. 10, L. 7, C. 18=42. 



DeLPHINIDxE. 



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. 



Phocmna 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 S (Mus. Oxford), C. 7, D. 12, L. C. 46=65. 



Neomeris phoccenoides (Mus. Leyden), C. 7, D. 13, L. 13, C. 30=63. 



Orca gladiator (Mus. Leyden), C. 7, D. 11, L. 10, C. 23 = 51. 



0. gladiator (Mus. Cambridge), C. 7, D. 12, L. C. 33=52. 



Pseudorca crassidens (Reinhardt), C. 7, D. 10, L. 9, C. 24=50. 



GloUocephalus melas (Mus. Roy. Coll. Surg.), C. 7, D. 11, L. 12, C. 28 = 58. 



G. melas (Middlesex Hosp.), C. 7, D. 11, L. 13, C. 28=59. 



G. 1. (Tasmania, Mus. Roy. Coll. Surg.), C. 7, D. 11, L. 14, C. 27 = 59. 



Pelphinus sinensis (Mus. Roy. Coll. Surg.), C. 7, D. 12, L. 10, C. 22=51. 



P. guianensis (Van Beneden), C. 7, D. 12, L. 14, C. 22=55. 



D. tursio (Mus. Leyden), C. 7, D. 13, L. 17, C. 25 = 62. 



P. heavisidii (Mus. Leyden), C. 7, D. 13, L. 15, C. 30=65. 



B. superciliosus (Mus. Leyden), C. 7, D. 13, L. 23, C. 30 = 73. 



D. delphis (Mus. Roy. Coll. Surg.), C. 7, D. 13, L. 24, C. 31 = 75. 



Lagenorhjnchus leucopleurus (Mus. Leyden), C. 7, D. 15, L. C. 59=81. 



L. albirostris (Mus. Cambridge), C. 7, D. 14, L. C. 67 = 88. 

 It will be seen from this Table that the total number of vertebras 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 Physeteridce, com- 

 prising the five genera placed at the head of the list, are all characterized by rather a 

 small number of vertebra; ; but among the other families there are many which have 

 quite as few as some of the former. For instance, the vertebral formulae of Platanista, 

 Beluga, Monodon, and Orca closely resemble that of Physeter. It is singular that the 

 most nearly allied genus, Kogia, differs so much in the number of dorsal vertebra;. 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 form 

 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. ^ ^ 



