AND AVES OF NORTH AMERICA. 



85 



Fig. 26. 



wider than long ; in our specimens and Gray's figure it is nearly twice as wide as long. It also appears that the 

 nasal bones do not entirely divide the nasal meatus, which they do in the three specimens under observation. On the 

 whole I am disposed to think that these forms belong to one rather variable species. It is true that Gray says "hind 

 foot fringed," but this I am inclined to think must be true to a very limited extent. There is only a keel in our 

 specimen, and Lilljeborg says there is no fringe in his. 



OSTEOLAEMUS TETRASPES, Cope. 



Proceed. Ac. N. Sci., Phila., 1860, 550. 



Crocodilus palpebrosus, var. 2, Cuvier. Oss. Foss. iii., t. 2 f. 6 (part). 

 Crocodilus trigonatus (part) Curvier. Oss. Foss. iii., 65. 



African Black Crocodile, Gray. Eept. British 

 Assoc, 1862, Zool. Section, 107. 



Osteolaemus tetraspes, Cope. Proc. Acad. N. 

 S., Phila., xii., 550. 



Crocodilus frontatus, A.Murray. Proc. Zool. 

 Soc, 1862, pp. 139, 213, fig. head, t. 29, by Ford. 

 Strauch, Syn. Cro., t. I., head (young). 



Halcrosia frontata, Gray, Ann and Mag. Nat. 

 Hist., 3d series, X., 277. 



Halcrosia afzelii Lilljeborg. Proceed. Zool. 

 Soc, Loudon., 1867, 715. 



Habitat, Gaboon Ogobai (Duchaillu). 



Calabar (Murray), Sierra Leon (Afzelius). 



This species was originally characterized as 

 follows : . 



Proportions of the head somewhat similar to 

 those of Crocodilus trigonops, Gray, of India. 

 Breadth of muzzle at ninth tooth equal to the dis- 

 tance between the external nasal orifice and anterior border of the orbit, and to the width of the table of the 

 cranium posteriorly. A short ridge in front of each orbit, directed obliquely inward. 



Teeth }|, rather compressed. Four nuchal shields, in a single transverse series ; four cervicals in pairs ; Dorsal 

 shields in six rows. Posterior extremities without fringe. Total length of the entire specimen, five feet. 



In addition to the characters given above maybe mentioned the strong concavity of the muzzle in the longitudinal 

 direction, and the prominence of the nares. The margins of the maxillary are very sinuous, being much contracted 

 behind the fourth and eleventh teeth. The derm of the head is thin and corneous, and divided into many segments, 

 which have a fine sculpture of straight lines radiating from the centre in each. The bones of the cranium are very 

 strongly pitted. Seventeen transverse series of plates between nape and posterior line of femora, 12 to union of 

 lateral caudal crests, and 19 from that point to end of tail. Nineteen cross-rows of large plates from ankle joint to 

 groin, on anterior face of limb. Counting similarly on the fore limb, there are 13 series. Only the two lateral dorsal 

 keeled ; keels of the outer of the first eight caudal annuli, low. 



Color everywhere black ; the plates occasionally with irregular olive lines. The young, according to Murray, 

 have olive bands on a yellow-brown ground, including two bands of plates, and separated by two bands. Total 

 length, five feet ; muzzle to supraoccipital ridge, 8 in. 9 lin. ; do. to posterior margin thighs, 2 ft. 7.6 in. 



Gray supposes this to be the " Crokodil noir du niger" of Adanson, and hence cites as its earliest name Croco- 

 dilus niger Latreille. Dr. Strauch, however, shows that this is probably the Crocodilus eatapJiractus Cuvier, and I 

 have pointed out that it cannot be the species of Latreille. 



AMERI. PH1LOSO. SOC. — VOL. XIV. 22 



