180 
SPOLlA ZEYLANICA. 
6. Association of Barnacles with Snakes and Worms. —The object 
of this note is to present to the readers of this journal a picture 
showing a group of barnacles belonging to two species attached by 
their stalks to the flattened tail of a sea-snake, Hydrus platurus. 
The attachment of barnacles to the skin of sea-snakes lias long been 
known, and was of course mentioned repeatedly by Darwin in his 
“ Monograph of the Cirripedes,” but a conspicuous example like the 
one here figured is not so commonly met with in Ceylon. The 
specimen was brought alive to the Museum on July 23, 1909. The 
two species of barnacles can be recognized in the drawing ; the one 
with complete white calcareous valves is Lepas anserifera , which 
Dr. Annandale referred to in Spolia Zeylanica , vol. III., p. 193, as 
being “ the commonest pedunculate form on floating objects in this 
part of the Indian ocean ” ; the other exposing the soft brown 
mantle which carries the greatly reduced calcareous valves is 
Conchoderma hunteri. 
The barnacles are not ectoparasites, as they do not feed upon the 
skin of the snake, nor do they assist the snake in any way; on the 
contrary, their presence must have seriously impeded the movements 
of the snake. Moreover, they thrive equally well when attached to 
floating bottles and drifting spars. So far as the snake is concerned, 
they are simply an incubus which cannot be shaken off, and the 
snake is merely their facultative vehicle. These barnacles are 
sedentary animals destitute of proper powers of locomotion, although 
capable of securing their own nourishment, but they have acquired 
a planozoic or passively vagrant habit, and they must be kept on 
the move. 
Their relation to the snake is somewhat analogous to a remarkable 
case of association between certain Hydroid polyps ( Stylactis minoi) 
and a small rock perch, Minous inermis, which was found by the 
Royal Indian Marine Survey ship “ Investigator ” in several places 
off the Indian coast, from the Mahanaddi to Calicut, in depths of 
45-150 fathoms. The skin of the fish is beset with the commensal 
polyps, which have never been found elsewhere, and Colonel Alcock 
(“ A Naturalist in Indian Seas,” London, 1902) thinks that they 
help to conceal the fish from its enemies, in that they play the same 
part which is, in other cases, performed by frond-like cutaneous 
filaments. 
The barnacle Lepas anserifera always, in my experience, occurs 
in pure culture when attached to bottles and Jogs, unaccompanied 
by the Conchoderma. But under these conditions, more particularly 
on logs, it is frequently accompanied by two Annelid worms, very 
distinct from each other, though both belonging to the same family, 
Amphinomidse. In August, 1907, and December, 1909, Lepas-logs 
were brought to me at the Museum, upon which I found numbers of 
these two species, Amphinome rostrata and Hipponoe gaudichaudi, 
not previously recorded from Ceylon, but known from the South 
