256 



GRIFFIN. 



Fig. 2. — Upper figure : 

 vertebra witli a hy- 

 papophysis projecting 

 from the lower side of 

 the centrum. Lower 

 figure : vertebra with- 

 out hypapophysis. 

 (From Boulenger. ) 



Luzon {Peters): Manila Bay {Boulenger) -. Baiitayan and Samar 

 (Bureau of Science collection.) . 



a'. Scale.s imbricate, large ventral shields, head covered 



by regular scales Subfamily Colubrinx. 



I. Hypapopliyses ° present on the vertebrse of the pos- 

 terior fifth of the trunk. 

 "'. Dentaiy bone of mandible loosely attached to the 

 apex of the articular, and freely movable upon 

 it; teeth very numerous and closely set, equal. 

 30 to 50 in each jaw; no interparietal shield. 

 Length, 490 millimeters. Black above, with a 

 white streak on each side. White below, with a 

 black spot on the outer end of each shield. 



Polyodontopliis bivittatus Boulenger. 

 Palawan {Boulenger) . Only the type speci- 

 men kno\^^l. 

 "-. Dentary bone not, or but sliglitly. movable on 

 the articular. 

 6'. Posterior maxillary teeth longest (IS to 40 in 

 all),' mandibular teeth sub-equal; eye mo- 

 derate or large with round pupil ; a pair of 

 internasal shields. Scales generally keeled. 

 Genus Natrix. 

 c'. Maxillary teeth not more than 30. the last 2 

 or 3 abruptly enlarged. 



'■ To note the presence or absence of the liypapophyses it is necessary to 

 make a slit in the posterior fifth of the abdomen; by pushing the viscera aside 

 and bending the backbone downward the ventral surfaces of the vertebroe may 

 be examined. If liypapophyses are present they appear as median ventral processes 

 of the vertebrae. 



"As the characters of the maxillary teeth are most important in classifying 

 snakes, it is necessary that they should be determined without mistake. The 

 method described by Stejneger, Herpetology of Japan and Adjacent Territory, 

 page 258, is most useful. "The examination of the dentition must be made very 

 carefully in order to avoid mistakes. The safest way is probably to dissect out 

 one of the maxillary bones. This can be done very easily by running the point 

 of a sharp knife between the supralabials and the underlying bone, cutting the 

 tissue along the whole length of the latter. By forcing the point of the knife 

 over the upper edge of the bone in the region of the eye the bone can be easily 

 lifted up and the connecting ligaments severed. The adherent tissue may be 

 carefully removed, though in most cases it is suflBcient to let it dry. The teeth 

 can now be examined conveniently. Care must be had not to mistake the space 

 left by a lost tooth for a natural interval; if a tooth has fallen out, a distinct 

 pit or depression is left on the alveolar edge of the maxilla. In counting the 

 teeth the second inner row of loose teeth which are only the resen'e teeth must 

 not be taken into consideration. If the specimen is so hardened that it is difficult 

 to open the mouth it should not be forced open by prying, a procedure apt to 

 ruin the teeth and break the lower jaw, but the thick muscle at the corner of the 

 mouth closing the jaws should be cut through on both sides. If properly done 

 the specimen need show no outward sign of mutilation. The maxilla after being 

 dissected out and cleaned should be placed in a small glass tube or vial and 

 provided with the same number as the snake, kept in the same bottle, or separately 

 togetlier with other preparations of the same kind." 



