288 CROCODILID &. 
CROCODILUS PLANIROSTRIS, Graves, Ann. Gén. Sc. Phys. ii. p. 848 
(1819). 
Crocodilus gravesii, Bory de St. Vine. Dict. Class. d’ Hist. Nat. v. 
p. 109 (1824); Dum. § Bibr. iii. p. 101 (1836). 
Habit remarkably stout. Snout short, perfectly flat above, with- 
out ridges. Four anterior nuchals on a transverse series and six 
posterior on two transverse series. Dorsal scutes in six longitudinal 
and 18 transverse series, with very strong, tubercular or recurved 
keels; lateral scales obtusely keeled. Scales on upper surface of 
limbs keeled, tubercular. Toes entirely webbed. No cnemial crest. 
4. OSTEOLEMUS. 
Osteolemus, Cope, Proc. Ac. Philad. 1860, p. 549 (1861). 
Halcrosia, Gray, Ann. § Mag. N. H. (8) x. p. 273 (1862), and 
Cat. Sh. Rept. ii. p. 19 (1872). 
Crocodilus, part., Strauch, Syn. Crocod. p. 28 (1866). 
16 or 17 upper and 14 or 15 lower teeth on each side; fifth 
maxillary tooth longest; fourth mandibular tooth fitting into a 
notch in the upper jaw. Snout rather short; nasal bones forming 
a septum dividing the nasal aperture; supratemporal fosse very 
small; a bony plate occupying the greater part of the upper eyelid. 
Splenial bones not entering the mandibular symphysis, which ex- 
tends to the fourth or fifth tooth. A dorsal shield formed of four or 
six longitudinal series of juxtaposed, keeled, bony scutes; gular and 
ventral scutes bony, not articulating together. 
West Africa. 
1. Osteolemus tetraspis. 
Osteoleemus tetraspis, Cope, 2. c. p. 550, and Proc, Ac. Philad. 1867, 
p- 209, and Tr. Am. Phil. Soc. (2) xiv. p. 85, fig. (1870). 
Crocodilus frontatus, A. Murray, Proc. Zool. Soc. 1862, p. 213, 
pl. xxix.; A. Dum. N. Arch. Mus, i. Bull. p. 88 (1864); Strauch, 
lc. pp. 87 & 84, pl. —, and Bull, Ac. St. Pétersb. xiii. p. 51 (1869). 
Halcrosia frontata, Gray, Ann. & Mag. N. H. (8) x. p. 273 (1862). 
nigra, Gray, Trans. Zool. Soc. vi. p. 153, pl. xxxi. figs, 1-6 
(1867), and Cat. Sh. Rept. ii. p. 20 (1872). 
afzelii, Lilljeborg, Proc. Zool. Soc. 1867, p. 715, figs. 
Head once and a half to once and two thirds as long as broad ; 
snout obtuse, its length exceeding a little its basal width; upper 
surface deeply honeycombed, without ridges; interorbital space 
deeply concave, narrow. Nuchal shield distinct from the dorsal, 
composed of two or three pairs of strongly keeled scutes, the ante- 
rior of which are very large; anterior part of nape with small, 
scattered, keeled bony tubercles, the largest of which may form a 
transverse series. 17 transverse series of dorsal scutes, the broadest 
composed of six scutes; keels very feeble on the two median series, 
