94 
above only as elongated hook-shaped borders produced backwards 
around the maxillaries. (Delphinoidea.) 
1. Lachrymal bones coalesced with the jugals. 
a. Costal cartilages not ossified. The tubercular and capitular 
articulations of the ribs blending together posteriorly. (Flower.) 
al. Maxillary bones with crests null or little developed. Teeth in 
great part with a complete cingulum, or a distinct tubercle at the 
base of thecrown. Eyemoderate. External respiratory aperture 
transversely crescentiform. 
: INIIDAE. (LXVI.) 
a2. Maxillary bones with large bony incurved crests. Teeth with- 
out cingulum or tubercle. Eye rudimentary. External respira- 
tory aperture longitudinal. a 
PLATANISTIDAE. (LXVII.) 
b. Costal cartilages firmly ossified. Posterior ribs losing their capitu- 
lar articulation, and only uniting with the transverse processes of 
the vertebre by the tubercle. (Flower.) 
DELPHINIDAE. (LXVIII.) 
2. Lachrymal bones distinct from the jugals. 
a. Costal cartilages not ossified. The hinder ribs losing their tuber- 
cular, and retaining their capitular articulation with the vertebra. 
(Elower.) 
ZIPHIIDAE. (LXIX.) 
B. Head not rostrated or marginated; snout high towards the front 
and projecting beyond the mouth. Skull raised behind and retrorsely 
convex. Supraoccipital projecting forwards laterally to or beyond the 
vertical of the temporal fosse. Frontals visible above as erect triangular 
or retrorsely falciform wedges between the maxillaries and supraoccipital. 
(Physeteroidea. ) 
PHYSETERIDAE, (LXX.) 
Il. Rostrum of skull prolonged into a slender, straight beak, the inter- 
maxillary and maxillary bones forming a cylinder, bearing teeth on its 
proximal portion. (/thabdosteoidea.) 
RHABDOSTEIDAE. (LXXI.) 
SUPER-FAMILY DELPHINOIDEA. 
LXVI. INIIDAE. 
Genus. 
Inia D’Orb. 
" Extinct Iniidae? 
Tretosphys Cope. 
Zarhachis Cope. 
Priscodelphinus Leidy. 
Izacanthus Cope. 
Lophocetus Cope. 
