618 ON A SKULL OF DISTIRA CYANOCINCTA. [NoV. 18, 



Snake, Distira cyanocincta, from Ceylon, belonging to the Museum 

 of the College of Surgeons, showing grooves not only upon all the 

 maxillary teeth, as normal in that genus of Sea-Snakes, but also upon 

 the mandibular teeth. The groove on the latter teeth, although very 

 shallow, was yet perfectly distinct when viewed under an ordinary 

 lens; it ran along the antero-outer side of the tooth. This appeared 

 to be the first notice of grooved mandibular teeth in a Snake ; but 

 the presence of a groove on the posterior maxillary teeth had been 

 several times recorded in Sea-Snakes, for the first time by Thomas 

 Smith, Phil. Trans, eviii. 1818, p. 472, who had remarked: — "In 

 this Serpent {Hydrus), as in many others nearly allied to it (les Hydres 

 of M. Cuvier), there are simple teeth on the same bone which sup- 

 ports the poisonous fangs. These teeth so much resemble the fangs, 

 that it requires a very close investigation to distinguish between them ; 

 and this arises from the simple tooth having not only a longitudinal 

 furrow exactly resembling the edges of the slit of the poisonous fiing, 

 but also a very visible cavity at the base, where the foramen occurs 

 in the others ; and I have even found a fine tube in a tooth of this 

 sort ; it was, however, confined to the parietes, and did not affect 

 the cavity of the tooth." 



Mr. Boulenger also exhibited three skulls of the Green Turtle 

 {Chflone mydas), likewise from the Museum of the College of 

 Surgeons. In one of these the prae- and postfrontal bones were in 

 contact, excluding the frontal from the periphery of the orbit; in 

 another, the frontal separated the prsefrontal from the postfrontal ; 

 whilst in the thiid, the former disposition was shown on the right 

 side and the latter on the left. Attention was drawn to the 

 variability of this character, because it had recently been proposed 

 to make use of it for diagnosing the genera of Turtles, the genus 

 C'helone, to which the Green Turtle belongs, being described by 

 Baur (Am. Nat. 1890, p. 486) as having the " Orbit formed by 

 prefrontal, frontal, postfionto-orbital, jugal, maxillary." It was 

 further observed that the same variability occurs, though not so 

 frequently, in the genus Thalassochelys. The skull of a half-grown 

 Loggerhead from Ceylon, preserved in the British Museum, had 

 the frontal bone excluded from the orbital periphery on the right 

 side and not on the left. That specimen had, bes-ides, the maxillaries 

 separated by the vomer, instead of the maxillary suture commonly 

 found in Thalassochelys ; a skull of Loggerhead in the College of 

 Surgeons was, in this respect, intermediate between the two extremes, 

 the jiraemaxillo-maxillary and maxillo-vomerine sutures forming an 

 X-shaped intersection. 



Mr. G. A. Boulenger, F.Z.S., read a paper upon the Reptiles 

 and Batrachians of Barbary (Morocco, Algeria, Tunisia), based 

 chiefly upon the notes and collections made in 1880-84 by 

 M. Fernand Lataste. 



This paper will be printed entire in the Society's ' Transactions.' 



