82 CHARLES CHILTON 



gins. On the whole I look upon this form as a modified descendant of 0. 

 chiliensis. No altitude is given for the locality at which it was taken, but 

 Portezuelo is a mountain pass about 590 metres high and I presume that the 

 animal is a true terrestrial one found at about this elevation above the sea. 

 The point of interest is that in the Juan Fernandez Islands we apparently have 

 the shore species Orchestia chiliensis extending on to the land and reaching 

 considerable altitudes, and in one case acquiring characters which make its 

 general appearance similar to that of purely terrestrial species of Talorchestia, 

 while in other examples no modification appears to have taken place. Presum- 

 ably the form I have described as a new variety has adopted a terrestrial mode 

 of life for some considerable time, though not long enough to have caused any 

 modification in the pleopoda, while the others that show no modification are 

 to be looked upon as forms that have more recently taken to life on land. 



The figures accompanying this paper have been prepared by Miss E. M. 

 Herriott, M. A., Assistant at the Canterbury College Biological Laboratory to 

 whom my thanks are due. 



The following is a list of the species with their distribution: — 



1. Orchestia chiliensis Milne Edwards. 



Chile, South America; New Zealand. 



2. Aora typica Kroyer. 



Widely distributed in all seas. 



3. Amphithoe femorata (Kroyer). 



South Pacific and South Atlantic. 



4. Jassa falcata (Mont.). 



Widely distributed in all seas. 



5. Caprella cornuta Dana. 



Rio Janeiro, Brazil. 



Orchestia chiliensis Milne Edwards. 



Orchestia cliiliensis Milne-Edwards, 1840, vol, 3, p. 18.^ 



Orchestia chiliensis Thomson, 1899, p. 199. 



Orc/iestia ciiiliensis Stebbing, 1906, p. 537. 



Orchestia serrulata Dana, 1853 — 55, p. 870, pi. 57, figs. 7 a— 1 ( J*), m — o($). 



Orchestia selkirki Stebbing, 1888, p. 603, pis. i, 2; 1906 p. 538. 



Localities. 



Masatierra, » under stones throughout the island,* S. P. E. No. 259. 

 About 20 males, averaging 15 mm. in length, though one with the second gnatho- 

 pod subchelate as in the male is only 8 mm. long; 12 females (or immature 

 males) averaging 10 mm. long. One male has abnormal second antennae. 



* The references are made by the year of pubHcation to the list on p. 92. 



