BARBADOS-ANTIGUA EXPEDITION 189 
water not more than a foot deep and on soft mud. At Barbados 
they are in deeper water and on sandy bottom. 
The all too familiar black sea-egg Diadema aniillarum is 
abundant here, as it is everywhere that I have collected in the 
West Indies. Several had established themselves on the stone 
steps leading down to the bathing place at the Dockyard. An- 
other well-known species had the same habitat as the Hipponde. 
This is Toxopneustes variegatus. This was found in abundance 
in Willoughby Bay and Falmouth Harbor. It resorted to the 
same method of concealment so generally adopted by its confrére, 
é. g. covering itself with debris of various sorts such as bits of 
eelgrass, small stones, shell, and even sand when it is available. 
One cannot help wondering whether there is any conscious 
intention connected with such proceedings. The writer has 
shown elsewhere? that the white sea-egg has something that may 
be called memory, and the question arises as to whether certain 
Eehini may not have the power of changing their habits, or as 
Jennings calls it, ‘‘modifiability of behavior,’’ in view of their 
past experiences. Such a power would certainly be of use to 
the species and encouraged and perfected by natural selection. 
Of course this could conceivably occur without any conscious 
adaptation of means to ends and in all probability does so 
oceur. 
Another explanation of this habit occurs to me. These forms 
are on mud-flats in shallow water which is unusually still and 
warm under the tropical sun. May it not be that this covering 
of foreign objects affords a sense of relief such as that exper- 
ienced by carrying an umbrella in the sun. Im other words, 
may not the habit be for the purpose, whether conscious or not, 
of securing a shade to mitigate the heat of the sun, which we 
know is unusually severe on these mud shallows? 
Another very common sea-urchin at Antigua is an Hchin- 
ometra which I take to be FE. lucunter or E. subangularis of 
Agassiz. In his ‘‘Revision of the Echini’’ he says that EL. viridis 
has a ‘“prominent bare abactinal system,’’ while the present spe- 
cies has the system beset with spines. This species is extremely 
abundant on rocky bottom near the Pillars of Hercules and also 
under rocks at Rocky Point. Right at the base of the high 
iNarrative of Bahama Hxpedition, 1895, p. 314. 

