1869. ] HULKE—CROCODILIAN SKULL. 171 
Now “ces deux petites proéminences” and the azygos process 
in the Oxford (Shotover) skull make it highly probable, I think, 
that the slender anterior nasals are really present in these Steneo- 
saurs; but the indistinctness of the sutures prevented their re- 
cognition. 
Not remembering one crocodilian skull, fossil or recent, in which 
the maxillaries entered into the construction of the external nostril, 
I examined, with special regard to this point, the large collection of 
recent skulls in the British Museum, comprising more than fifty 
skulls, including every known species of the gayial, crocodile, and 
alligator types, and also all the skulls in the Museum of the Royal 
College of Surgeons; and I did not find one where the maxillaries 
formed part of the opening of the anterior nostril. In every instance 
this was formed of the preemaxillaries alone, as in the Gayials, or by 
the premaxillaries and the nasals. I could not find one example 
of a median process projecting forwards from the posterior border 
of the nostril formed of the preemaxillaries. Such a process always 
consisted of the anterior extremities of the nasal bones, which either 
entered the posterior border of the nostril in the plane of the ex- 
ternal opening (in most alligators), or below this plane (in many 
crocodiles, where the junction of the premaxillaries behind the 
nostril concealed and overlay the front ends of the nasals, which 
descended into the nostril beneath them). In some skulls the nasal 
process received a small accession from the premaxillaries; but 
this was always subordinate to it, and never reached beyond its 
base. In Gavyials also (where the intermaxillaries alone enclose 
the nostril) these minute projections of the intermaxille into the 
nostril were sometimes present, but they were dwarfed and in- 
significant. 
Should my suspicions prove correct, and Sten. rostro-minor and the 
Oxford (Shotover) skull be found to have the slender nasals of Sten. 
Manselii, this last will still be distinguished from Sten. rostro-mior 
by the different proportions of its skull, and the number and the 
distribution of its teeth. 
What are the two large triangular bones in Sten. Manselit which 
descend from the forehead to the middle of the snout? Evidently 
they correspond to the bones marked aa, fig. 5, pl. x., ‘Ossemens 
Fossiles.’ They are, I imagine, the principal frontal, retaining perma- 
nently in the adult Stencosaur the median suture which primitively 
divides it in the embryonic crocodile. Attaining in the Steneosaur 
a very large size, the divided frontal thrusts aside the posterior ends 
of the nasals, and, uncovered by these, forms so large a part of the 
surface of the snout. Its excessive descent, however, is less than 
at first sight appears ; for it is well known that in existing crocodiles 
the frontal, which seems to end in front of the orbit, really only 
disappears from the surface here, and beyond this, hidden and over- 
lain by the prefrontals and nasals, it stretches forwards a long dis- 
tance—in Croc. vulgaris exceeding one-third of the distance between 
the orbit and nostril, 
