TÅ 
considerably widened (Fig. 14), and also the legs and antennæ 
more or less widened, resembling, with their splendid coloration, 
branches of one of those Florideans with broad, flat, iridescent 
»leaves". The result was very striking. Unfortunately the colour, 
also the eye spots, has disappeared in the preserved specimens 
(a second one was taken later on), so that the figure cannot give 
any approximate impression of what it looked like when alive. — 
Also at the little island of Taboga in the Gulf of Panama I found 
a species of this shrimp (Fig. 13). It belongs to the genus Hy- 
menocera. 
Another shrimp (a Hippolytid) mimicking algæ was observed on 
Coral blocks near Honolulu (Fig. 12). In this case it is fine, branch- 
ing outgrowths on the carapace and legs, which give the appear- 
ance of fine algæ. It resembles very strikingly the dirty vegetation 
of small algæ, hydroids a. 0. organisms growing on the underside 
of old coralblocks, where the water is impure. Although wonderfully 
deceptive, when alive, this form is hardly so remarkable as //y- 
Menocera. 
It should be pointed out that these two cases do not quite go 
together with the usual adaptation of animals living among algæ. 
These forms do not live among algæ and are not adapted to hiding 
themselves among algæ. They are living free, but, so to say, ex- 
Pect to be taken for algæ themselves. 
Small shrimps are often found living on Crinoids or Echinoids, 
and especially on corals, and are then colored exactly like their 
host and very difficult to discern. I have observed a number of 
Such cases, but cannot give the details at present.) — Coutiére”) 
records the case of the Alpheid Arete dorsalis living on Hetero- 
cenfrotus mamillatus and on Echinometra »lucunter« (for Ech. 
mat!hæi). Alcock (Op. cit. p. 112) records similar observations, 
especially of Crustaceans living on Spongodes. 
The typical cases of adaptation to life among algæ are especially 
found among the Caprellids; they might be said to represent the 
Phasmids and Geometrid larvæ among marine animals. Although 
”) See also F. A. Potts. Researches at Murray Island. Yearbook of the 
i Carnegie Inst. No. 13. 1914. p. 209. ; 
) H.Coutiére. Note sur le commensalisme de PAréte dorsalis. .... 
Bull. Mus. d'hist. nat. 1914. p. 58. 
