ZOOLOGICAL SOCIETY 



BULLETIN 



Published by the Neiv York Zoological Society 



Vol. XVI 



JULY, 1913 



No. 58 



SOME RARE CROCODILES 



By Raymond L. Ditmars. 



E 



IGHT species of croeodilians are now 

 on exhibition in the Reptile House and 

 with this thoroughly representative 

 series at hand the collection of our big 

 saurians deserves special review. Following- 

 are the species represented: Indian Gavial, 

 Gavialis gangeticus; Senegal Crocodile, Cro- 

 codilus cataphr actus; Salt Marsh Crocodile, 

 Crocodilus porosus; Orinoco Crocodile, Cro- 

 codilus intermedins; American Crocodile, 

 Crocodilus americanus; Broad-nosed Croco- 

 dile, Osteolaemus tetraspis; American Alligator, 

 Alligator mississippiensis, and the Rough- 

 eyed Caiman, Caiman sclerops. 



Seven years after the opening of the Rep- 

 tile House, the author prepared a very full 

 paper covering the care and growth of the 

 American Alligator.* This paper reviewed the 

 hatching and rearing of alligators in the 

 Zoological Park and dealt with the practi- 

 cability of alligator farming. Since the pub- 

 lication of this review our observations on 

 the croeodilians have been continued under 

 what we consider the best possible condi- 

 tions. The tanks for the croeodilians are 

 commodious, giving the reptiles ample room 

 for swimming, while they are provided with 

 banks floored with sand upon which the 

 animals may emerge from the water. Dur- 

 ing the cold months of the year the water 

 of the tanks is kept heated, by means of 



a submerged pipe, to a temperature varying 

 between 90 and 95 degrees Fahrenheit, 

 while the temperature of the Reptile House 

 ranges from 75 to 85 degrees F. We 

 find that if these reptiles are kept in water 

 of a lower temperature than that mentioned, 

 during the cold months they feed indifferently 

 and irregularly, even though the temperature 

 of the air is satisfactory. They prefer to 

 pass the greater part of their time in the water, 

 consequently this medium, to promote normal 

 development must have a high temperature. 

 Another point to be noted is the tendency 

 for crocodiles to drown in cold water. 



They cannot endure water at anywhere 

 near the temperature of the hardy alligator 

 and if thoroughly benumbed will sink to the 

 bottom and die. This may be accounted for 

 by the fact that the alligator extends into 

 latitudes where hibernation is necessary, 

 while no species of crocodile ranges far 

 enough away from the tropical zones to en- 

 counter actually cold water at any time of 

 the year. 



While much has been alleged about the 

 slow growth of croeodilians, we have found that 

 theory has largely entered into the resulting 

 descriptions of development. There is some 

 foundation for the theoretical side of the 

 question, for of all reptiles, tortoises and 

 croeodilians grow slowly in comparison with 



♦Growth of the Alligator; 11th Annual Report of the New York Zoological Society. 



