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14. A Small Collection of Amphipoda from 
Juan Fernandez. 
By 
DpeeHA REES CHILTON 
Professor of Biology, Canterbury College, New Zealand. 
With 4 textfigures. 
The Amphipoda described in this paper were collected at the Juan Fer- 
nandez Islands by Mr. K. BACKSTROM of the Swedish Pacific Expedition of 
1916-17. For the opportunity of examining them I am indebted to the leader 
of the expedition, Professor C. SKOTTSBERG and to- Professor T. ODHNER of 
Stockholm. The collection is a small one including only five species and a 
new variety of one of the species, the others being already known. I give 
below a list of the species with a note as to the distribution of each. 
The only point calling for special attention concerns the first species, 
Orchestia chiliensis Milne-Edwards. This has long been known from Chile and 
from New Zealand; in the latter country it is extremely common in most places 
on the sea shore, and does not appear to extend far beyond high water mark, 
although under favourable conditions it may be found at some little distance 
from the beach. In Juan Fernandez it appears to be common also, one bottle 
being labelled »under stones throughout the island», but here it appears to 
extend also to considerable distances from the shore and to heights above the 
sea up to 500 metres. The tube labelled »500 m. above sea level» contains 
several specimens similar in size and structure to those collected on the sea 
shore. Other specimens labelled »in a brook» are much smaller, but I think 
are only to be looked upon as young forms of the same species and.the same 
is true of another tube labelled »under stones,» the altitude of the last two 
not being given. Another specimen of larger size, 13 mm. in length, labelled 
»Portezuelo, under stones» shows certain differences, and I am describing it as 
a new variety. Its antennae and peraeopoda are much longer and more slen- 
der than in the typical form of O. chi/iensis, and the second gnathopod also 
shows some differences in the shape of the palm. The pleopoda are, however, 
well developed, showing no reduction in size such as is found in terrestrial 
species of Parorchestia, and the telson has numerous spines on its lateral mar- 
6 — 20131. The Nat. Hist. of Juan Fernandez and Easter Isl. Vol. III. 
