| OCR Text |
Show 1895.] TEETH OP CERTAIN POISONOUS SNAKES. 817 teeth of these Snakes are on the external face of the tooth, and are slightly to one side of the axis (PL I. fig. 16) (this is also the case in Oxybelis). The blood-vessels supplying the maxillary teeth form considerable blood-sinuses around the bases of the large median teeth; this was more particularly noticed in D. prasinus. These sinuses are in direct continuity with the blood-vessels in the pulp-cavity of the tooth, and lie at the base of the large longitudinal furrow between the pterygoid and the maxilla. They just underlie the glandular epithelium of the mouth, being separated from it only by a thin layer of connective tissue. The mandibular teeth increase in size from the first to the fifth in D. mycterizans and then follows a series of much smaller teeth; in D. prasinus they increase in size from the first to the third, the latter being the largest tooth in the head, and these are then followed by 10 smaller teeth. Genus OXYBELIS. Species examined :-0. fulgida. The poison-gland is very clearly defined and the superior labial gland is exceedingly long and narrow; it reaches to the anterior extremity of the maxilla and consists of much smaller lobules than the poison-gland. The inferior labial gland is also greatly elongated, reaching from the anterior extremity of the mandible almost to the articular condyle, and is more extensive than that of any other of the Snakes examined. The Harderian gland (PL X L I V . fig. 20) is precisely similar to that of Dryophis. The maxilla (PL X L I V. fig. 21) possesses more teeth than that of any other of the Snakes examined, there being 20 in one uninterrupted series. The first 17 are equal in size and much curved; the posterior three are a little larger, compressed laterally, and the external face of each possesses a very shallow groove. The muscular folds surrounding these three posterior teeth are not united in front, and in consequence of a thin muscular fold across the base of the anterior grooved tooth the poison-duct in this Snake is placed in communication with the interior of the mouth before it is with the groove of the tooth (PL X L I V . fig. 22). The mandibular teeth are 18 in number. The first 8 are of equal size and slightly larger than the maxillary teeth ; these are followed by 10 much smaller closely-set teeth. The only difference between this genus and the preceding one (Dryophis) is in the absence of the large median maxillary fangs and in the circular pupil, the latter being elongated in a horizontal direction in Dryophis. Genus ETEIRODIPSAS. Species examined:-E. colubriens. The poison-gland is clearly defined and the lobules are very . small; the superior labial gland is rather more extensive than usual |
