236 MAJOR F. WALL, I.M.S., C.M.Z.S. 



developed or absent. Costals , —anterior 29 to 41, midbody 33 to 46, posterior 28 



to 42, feebly imbricate anteriorly, feebly imbricate or juxtaposed posteriorly. 



Ventrals ,—227 to 300, entire or a few divided posteriorly, about twice or less than 



twice the breadth of the last costal row. 



Habitat. — From the Persian Gulf to Australia and as far north as the Loo Choo 



Islands and Japan. 



Colour. — The adornment of this species is very diversified, and at least six well 



defined varieties may be met with. 



(i) Completely banded. This is seen more often in young specimens, but in 

 rare instances, the bands are preserved towards or into adult life. 

 Figure 51 furnishes a good illustration from the specimen presented by 

 me to the British Museum. It was collected by Mr. Owston in the Loo 

 Choo Islands. The specimens of godeffroyi (Boulenger) in the British 

 Museum which I cannot separate from omata are very similar. The bands 

 taper ventrally, are complete anteriorly, but incomplete ventrally in 

 the hinder part of the body. A specimen from Karwar in the Bombay 

 collection has dorsal bars anteriorly, and nearly complete tapering 

 annuli behind. This form is analogous to variety (1) of viperina. 



(2) Forma tvpica (Gray). Dorsum beset with blackish bars which are discrete, 



and broader than the intervals. Much the commonest variety in 

 adults and young. The specimens of pachycercus in our National 

 Collection which I cannot distinguish from omata are much the same, 

 but the bars are less distinct. It is analogous with the forma typica of 

 viperina. 



(3) Like the last but the dorsal bars modified into rhombs, the angles of many 



of which may be confluent vertebrally. Polyodonta (Jan) which I 

 regard as merely a variety of ornat.i is a good example. It is very 

 analogous to var. (3) of viperina. 



(4) Dorsum ornamented as in "forma typica," and the costal region with a 



single, more or less complete, series of large spots or bars alternating with 

 the dorsal series. It is not uncommon, Jerdon's example in the British 

 Museum (Fig. 50) is an excellent illustration. It is from Madras. A 

 specimen in the Colombo Museum (No. 127) is presumably of local origin. 

 A young specimen in the Indian Museum presented by Captain Lloyd, 

 I.M.S., is from Sandaway Island on the Burmese coast. In this the 

 costal spots are smaller than in the other examples. Of this variety is, 

 also, I consider, frontalis (Boulenger, non Jan). It is very comparable 

 to var. subcincta of spiralis. 



(5) momata (Gray). The whole dorsum black as though all the dorsal bars of 



" forma typica " had become confluent. The band so produced occupies 

 the upper two-fifths or half of the body depth, and is sharply defined, 

 reminding one of the colour disposition of the common variety of 

 Hydrus platurus. It is a rare form. The type, viz. inornata (Gray), is 



