100 BARBOUR: ZOOGEOGRAPHY. 



on which occurs a pallid form varying from T. hraminus in the following char- 

 acters: — a wide rostral, a preocular broader than nasal or ocular, and 24 rows 

 of scales around the body. There are many points of close similarity in pro- 

 portions and squamation between these two forms; the only really noteworthy 

 deviation of T. socotranus Blgr. from T. hraminus being the addition of four 

 rows of scales around the body. 



Glinther in his article on snakes in the Encyclopaedia Britannica, 1881, 

 p. 190, says: "Snakes are the most stationary of all vertebrates; as long as a 

 locality affords them a sufficiency of food and shelter to w'hich they can readily 

 retreat, they have no inducement to change it. Their dispersal therefore must 

 have been extremely slow and gradual." Again on p. 194 he remarks in direct 

 allusion to the forms under discussion: "Some of the small species have a wide 

 range, having been probably transported by accident on floating objects to 

 distant countries." It seems hardly credible that so small and delicate an 

 organism as T. hraminus would live under the peculiar conditions to which 

 travel on some "floating object" would subject it; yet it is possibly sometimes 

 carried about with bulbs and roots transported by man. The oft-quoted story 

 of a boa floating two hundred miles from the coast of South America to the 

 Island of St. Vincent, twisted round the trunk of a "cedar tree," has little bear- 

 ing on the possible dispersal of a Typhlops. South American rivers more than 

 any others are prone to float great matted masses of vegetation to sea, and this 

 occurs quite frequently during the heavy rains. This, however, could hardly 

 ever occur in the case of the greater Indian rivers, for instance; for their courses 

 now, at any rate, lie largely through even plains, perhaps deforested by man for 

 cultivation, — but also largely through sandy wastes. The Irrawaddy does 

 frequently carry down considerable masses of vegetation, but these are not 

 buoyant, and are wave-beaten and saturated with sea-water as soon as they 

 emerge from the delta into the Bay of Bengal. Flotsam carries with it but few 

 terrestrial animals compared to what was once supposed. 



Possibly this archaic form, or ancestors of this form, followed some such 

 route of dispersal as Osborn has figured for the elephants (c/. Century mag., 

 79, p. 829, map). That this form itself dispersed and not its ancestors, seems 

 likely from the fact that no definitive variation occurs within the species itself. 



During a visit to Calcutta it was a matter of great interest to learn of the 

 newly discovered T. hraminus arenicola Annandale (Mem. Asiat. soc. Bengal, 

 1, p. 192). This is a peculiar, almost pigmentless, form from "the desert tract 

 of Southern India" in the district of Madura. Dr. Annandale describes two 



