IOWA ACADEMY OF SCIENCES. 
35 
white. This may also be true of bright red gorgonians, 
pennatulidse and sponges, with their glassy spicules, and red 
corals, with their very large nematocysts. 
The various cases of commensal association, such as the 
ophiurians, resembling the brilliant gorgonians upon which 
they climb, would thus be readily explained as instances of 
protective resemblance. Among the Crustacea the numerous 
cases of bright red, red and white or green coloration may be 
possibly capable of explanation along the lines of directive 
coloration, whereby the individual may recognize its own 
species, and thus the meeting of the sexes be facilitated. It 
must be remembered that many deep-sea crustaceans have 
excellent eyes. In short, these brilliant colors in all groups 
can, according to this theory, be explained by reference to the 
same laws that prevail on land or in shallow water. 
Beddard regards as a fatal objection to this theory the fact 
that the eyes of many deep-sea dwellers are apparently now in 
the process of degradation. But the same thing is found 
among the mud-dwelling mollusca and the sponge-inhabiting 
Crustacea, such as Aljolieus in shallow water. Mud and sponges 
are also found in deep water and have their inhabitants as 
well. Again there are doubtless vast areas in which the phos- 
phorescence is exceedingly feeble or entirely wanting, and yet 
they are not necessarily or even probably tenantless. In such 
places the possessors of eyes would find them worse than use- 
less and gradual atrophy would ensue. I must confess to an 
utter inability to see the force of Beddard ’s so-called ‘‘fatal 
objection. ” 
A side-light is thrown on our discussion by some of the well 
known facts concerning cave fauna. These facts are: 
First . — Cave animals are almost universally colorless, or at 
least are not brightly colored. 
Neco?id.— I have been unable to find any record of phosphor- 
escence among cave animals. 
Third . — Blind animals are common in cave fauna. 
Fourth . — No cave animals, so far as I know, are character- 
ized by greatly enlarged eyes. 
It would thus seem that the absence of phosphorescence in 
* Beddard explains such cases by spying- that the parasite actually assimilates and 
deposits in its own skin the pigments of the host. (Loc. Cit., p. 38.) When we consider 
that the colors of the gorgonians are in the hard and jagged spicules alone we cannot 
withhold our sympathy from the ophiurian, which has either to eat such unattractive 
fare or in some way to absorb it through the skin. 
