222 PROCEEDINGS OF THE AMERICAN ACADEMY. 



The only place where I found this copepod was in a cave in the 

 small ledge-like island across from the bathing place at Agar's Island 

 (see the map in Mark, : 09, p. 2). The cave is a small one and is at the 

 south-west end of the ledge. I have never seen a specimen of Lampoi- 

 dopus that was taken anywhere else and it is my belief that the ani- 

 mals are not found outside the cave, at least, not any distance from it. 

 Collections were not made in the water between Agar's Island and the 

 ledge, but there were some from the ship channel, and this is rather 

 close to the place where the cave is located in the ledge. The animals 

 were very abundant in the cave ; young in all stages of development 

 as well as adults were taken. The only haul was made at high tide. 

 A small net was fastened to the end of a pole and swept through the 

 water inside the cave. 



The most interesting thing connected with the finding of this co- 

 pepod is that, so far as I know, the small cave is the only place near 

 Agar's Island where the "hat" or "shade " coral {Agaricia fragilis) is 

 found. Furthermore the coloration of the copepod is strikingly like 

 that of the coral, the same brownish tint characterizing both. It is my 

 belief that this is an example of protective coloration. If so it offers a 

 new case among Copepoda especially, and plankton animals generally. 



According to Steuer (: 10, p. 282), complete lack of color, and hya- 

 linity, is the best adaptation to a plankton life. Blue and violet are 

 adaptive to the blue water of warm seas, and red, brown-red or dark vio- 

 let belong to the abyssal zooplankton, Steuer also states (p. 283) that 

 creeping or swimming animals from the Sargasso Sea are characterized by 

 brown or green shades. Taking these general observations into con- 

 sideration with the circumscribed distribution of Lampoidopus, and the 

 fact that the other copepods obtained are transparent and colorless or 

 else bluish, it seems reasonable to regard the color of Lampoidopus as 

 protective. It is certainly suggestive of this that these little copepods 

 should have a coloration that is unusual in the group as a whole, that 

 their distribution should be so limited, and that at the same time their 

 colors should be so similar to that of the corals. I did not make col- 

 lections in other caves, but it would be interesting to know if these 

 copepods are found elsewhere and, if so, whether they are found gen- 

 erally with Agaricia. 



Calanopia americana Dahl. 



Plate 2, Figures 12, 15; Plate 3, Figures 27, 32; Plate 4, Figure 39. 



These copepods are very abundant around Agar's Island and very 

 rare in the locality of North Rock. They may be easily recognized by 

 their comparatively large size, the pointed posterior borders of the thorax 



