922 DR. GWYN JEFFREYS ON THE MOLLTJSCA OF THE [NoV. 29, 



sa])ralabials, separated from orbital by a single row of infraorbitals. 

 10 iiifralabials. Temporal region covered with minute granules. 

 Gular fan small ($ ). 



Body scarcely compressed, covered with small smooth granular 

 scales,'those on the belly a little larger. Tail cylindric, not much 

 longer than head and body, covered with elongate, slightly keeled 

 scales. 



Limbs short, extended forwards, the extremity of longest finger 

 reaches the nostril, and the extremity of longest toe the shoulder. 

 Tibia two thirds the length of the head. Fingers and toes short, 

 with well-developed dilatations. 



Light grey above (not bleached), with pure white spots and a 

 dark-brown network ; tail encircled by complete dark-brown annuh. 

 Beneath white, with a few dark spots. 



(tail injured). Half-grown. 



Length from tip of snout to extremity of tail. . 0-113 0-089 



Length of head to ear-opening 0-014 0-011 



Length of body from ear-opening to vent ... . 0-041 0-028 



Length of tail 0058 0-050 



-"o" 



Length of fore limb 0*0195 O'OIG 



'o 



Length of hind limb 0-029 0-0215 



D 



Two specimens of this very distinct species have been recently 

 obtained by the Royal Belgian Museum from M. A. Boucard, 

 together with other Reptiles and Batrachians from Yucatan. Among 

 these were several specimens of the highly interesting Triprion 

 petasatus, Cope (Proc. Acad. N. S. Phil. 1866, p. 127), a Frog 

 which does not appear to have reached European collections before. 



This Anolis is named in honour of my friend M. Le'on Becker, 

 the distinguished Belgian Arachnologist. 



4. On the Mollusca procured during the ' Lightning ' and 

 'Porcupine' Expeditious, 1868-70. (Part IV.') By 

 J. GwYN Jeffreys, LL.D., F.R.S., F.Z.S. 



[Eeceived November 4, 1881.] 

 (Plates LXX., LXXL) 

 CONCHIFERA {concluded). 

 Family XVI. Mactrid^. 

 I. Amphidesma castaneum, Montagu. 



Bonax castanea, Mont. Test. Brit. x\pp. p. 5/3, t. 17. f. 2. 

 A, castaneum, B. C. ii. p. 413, pi. viii. f. 1 ; v. p. 188, pi. xliii. 

 f. 1. 



' For Part I. see P. Z. S. 1878, p. 393 ; for Part II. see P. Z. S. 1879, p. o53; 

 for Part III. see P. Z. S. 1881, jx 693. 



i 



