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217 
CROCODILUS SIAMENSIS. 
By Ma.tcoum A, SMITH. F.Z.S. 
Wirtn 3 PLatTeEs. 
Crocodilus siamensis was erected by Schneider in 1801, on a 
skull brought to Europe by the French missionaries to Siam. Mouhot 
Jater obtained a young specimen in Cambodia, which is now in the 
British Museum, and it is also known by one or two specimens from 
Java. These appear to be the only known records of this creature. 
In publishing a list of the crocodiles, chelonians and lizards of 
Siam in this Journal three years ago, I stated that C. palustris Lesson, 
the Indian “ mugger”, was an inhabitant of the country, basing my 
statement upon some juveniles and a dried skin. I have since examined 
a large number of specimens, both alive and dead, and have discovered 
my error. The inland or fresh-water crocodile of Siam is C. siamensis, 
and, as I shall presently endeavour to show, C. palustris does not exist in 
the country at all. 
Most of the characters which distinguish Q. siamensis from its 
allies, C. palustris and porosus, have already been enumerated, but 
I propose now to review them in greater detail, and to add some others 
which have so far escaped observation. ‘ 
The head*. 17 or 18 upper teeth on each side, 4 teeth in each 
praemaxillary ; 15 lower teeth on each side, the mandibular symphysis 
extending to the fourth tooth. 
Snout from once and two-thirds to once and five-sixths as long 
as broad at the base; interorbital breadth greater than the vertical 
diameter of the orbit ; a thick, fairly distinct curved ridge, present in 
most specimens, extending from the anterior extremity of the orbit for 
a short distance ; interorbital ridge, much narrower than the prae- 
orbital, commencing from in front ofa line drawn through the middle of 
the orbit, and extending to a line drawn across its posterior extremities ; 
in some examples it is very poorly developed. Praemaxillo-maxillary 
suture on the palate directed backwards. 
The integument. One or two pairs of postoccipital scutes. Four 
large nuchals in a square with a smaller one on each side. Dorsal 
$$ $$, — 
*The changes which take place in the skull during growth are econsider- 
able. and the proportions given here apply to adults only, or at least half-grown 
individuals. 
VOL, III, NO, III, 1919- 
