A SMALL COLLECTION OF AMPHIPODA FROM JUAN FERNANDEZ. 85 



ever, may be due to the selection of larger specimens by the collector, though 

 when collecting this species on the coast of New Zealand I have usually found 

 the males fairly numerous. The other specimens which have the second 

 gnathopod small and not subchelate are considered to be either females or 

 immature males, all of these are smaller than the males. 



The -specimens in tube No. 729 marked »Masatierra, under stones» are I 

 think young forms of the species now under consideration. The same is true 

 of those in tube No. 494, labelled »Masatierra, among withered leaves. > None 

 of the specimens in these two tubes shows the adult characters of the male or 

 bears eggs. 



The specimens in the two tubes, No. 327, 

 are of special interest as they were obtained 

 500 metres above sea level. In one tube are 

 about a dozen large specimens, averaging about 

 12 mm. in length. One of these is a male, 

 fully developed^ showing the usual male char- 

 acters as mentioned above and having the 

 expansion of the joints of the fifth peraeopod 

 slightly greater than in any of the specimens 

 in tube 259 which, presumably, were obtained 

 from about the sea level. The other specimens 

 in tube 327 are apparently females or young 

 males. One of them which I dissected was a 

 female with about 7 or 8 eggs in the brood 

 pouch. Most of these eggs were very hard, 

 almost stony, but whether this was the result 

 of the action of the preservative or from path- 

 ological cause, I cannot say. In the other 

 tube, also marked »No. 327, under stones, 500 

 metres above sea level, » were small specimens 

 about 4 mm. in length which are doubtless 



young of this same species. F'g- ^- G, Orchestia chiliensis. Head 



° - , . - , . , , and antennae of male with abnormal 



Of the specimens found »m a brook* number of joints in the second 



No. 724, two appear to be immature males antenna. 



showing male characters in the gnathopods, 



and the rest apparently females. These two males illustrate to some extent 

 the stages passed through in the development of the adult male characters. 

 The larger one about 6 mm. long, has the first gnathopod (fig. i, C) well devel- 

 oped, the carpus and propod being produced posteriorly into the characteristic 

 pellucid lobes but not to the same extent as in more adult males, while there 

 is no sign of a similar lobe on the merus; the second gnathopod (fig. i,D) 

 has the propod large, widening a little distally, the palm nearly transverse and 

 regularly even with a small groove as usual for the reception of the tip of the 

 finger. In the other much smaller specimen, the first gnathopod (fig. i,E) is 

 stouter than in the females, but none of the pellucid lobes are developed, the 

 palm being straight or slightly concave and not extending beyond the tip of 

 the finger; the second gnathopod (fig. i,F) is rather stouter than in the female 



