58 REPTILES. 



** Labial shields occupying only the front half of the lips : eyes over 

 the fifth or sixth shield : hinder part of lips covered with small 

 scales : ventral scales generally free, tivu-rowed^ forming a keeled 

 ridge, or sometimes united in pairs into a flattish six-sided 

 shield. 



9. Hydrus. 



Scales elongate, lanceolate ; of the neck longer and naore acute, 

 keeled : eyes small ; pupil round. 



Hydrus, Gray, Zool. Misc. 60, 1842. Hydrus sp., Shaw,Zool. 

 iii. 558. Pelamis sp., Merrem. 



1. The Sea Snake. Hydrus major, Shaw, Zool. iii. t. 124. 

 Gray, Zool. Misc. 60. Pelamis Shawii, Merrem, Tent. 139? Hy- 

 drus Stokesii, Gray, in Stokes's Australia, App. 4, t. 3. 



White in spirits ; dorsal and ventral edge with alternate broad 

 and narrow black cross-bands ; sides with a series of small roundish 

 spots, becoming nearly uniform whitish when adult ; labial shield 

 reaching to the eye. 



Var. 1. Hinder labial shield small, triangular, with the scales 

 above them larger and transverse. 



a. In spirits. Half grown. Anterior ocular moderate ; hinder ocu- 



lar shields 3, small ; ventral shields almost all separate. India. 

 Old collection. Described by Dr. Shaw. 

 H. major, Shaiv, Zool. 



b. Inspirits. Half grown. Anterior ocular 1, posterior 2; the 



front ventral shield united into cordate, smooth plates ; rest 

 lanceolate, separate. Port Essington. Presented by the Earl 

 of Derby. 



c. In spirits. Very young. Scales short, blunt, polished, very ob- 



scurely keeled : white; back with alternate broad and narrow 

 black cross-bands ; sides with a series of roundish black spots, 

 and with an alternate series of small black spots and short 

 cross-bands. Port Essington. Presented by the Earl of 

 Derby. 



Var. 2. Stokesii. The hinder labial shields moderately large, 

 subtriangular, rather high, as large as the series of scales above 

 them. 



d. In spirits ; bleached. Adult. Hinder ocular 2. Australian 



Ocean. Presented by Captain Stokes, R.N. 

 Hydrus Stokesii, Gray, I. c. t. 



