PHYSETER. 69 
the surface, usually in the form of a transverse, subcrescentic, 
valvular opening, situated on the top of the head. Hand always 
pentadactylous, the first and fifth digits however but little 
developed. No cecum, except in Platanista. 
Family I.—PHYSETERIDAS. 
No functional teeth in the upper jaw. Mandibular teeth 
various, often few in number. Bones of the cranium raised so as 
to form an elevated prominence behind the nostrils. Pterygoid 
bones thick, not involuted to form the outer wall of the post- 
palatine air-sinuses. Transverse processes of the arches of the 
dorsal vertebree, to which the tubercles of the ribs are attached, 
ceasing abruptly near the end of the series, and replaced by pro- 
cesses on the vertebre at a much lower level, not on a line or 
serially homologous with them, but anteriorly with the heads of 
the ribs, posteriorly with the transverse processes of the lumbar 
vertebre. Costal cartilages not ossified. 
Subfamily I.—Puysererine. 
Numerous teeth in the mandible which are not set in distinct 
bony alveoli, but in a long groove imperfectly divided by partial 
septa, and held in place by the strong fibrous gum which surrounds 
them. No distinct lachrymal bone. Cranium strikingly asym- 
metrical in the region of the narial apertures, in consequence of 
the left opening greatly exceeding the right in size. 
Genus I.—PHYSETER, Linneus (1748). 
Upper teeth of uncertain number, embedded in the gum; man- 
dibular teeth from twenty to twenty-five in each ramus, stout, 
conical, recurved, and pointed, without a coating of enamel. 
Upper surface of cranium concave. Rostrum greatly elongated, 
tapering gradually to the apex from its broad base. Mandible 
very long and narrow, the symphysis more than half the length 
of the ramus. Atlas free, the remaining cervical vertebra united 
into a single mass. Eleventh pair of ribs rudimentary. Head 
about one-third of the length of the body, very massive, high, and 
truncated. Nasal opening single, longitudinal, slightly to the left 
of the median line of the head. Fore limb short, broad, and 
truncated. Dorsal fin a mere low protuberance. 
Vertebre.—C. 7, D. 11, L. 8, Cd. 24; total 50. 
1. PHYSETER MACROCEPHALUS, Linneus (1766). 
Sperm Whale; Cachalot. 
Body above very dark, occasionally black, fading gradually on 
the sides and belly, silvery gray on the chest. 
