86 THE VOYAGE OF H.M.S. CHALLENGER. 
Observations.—In general, the shape of this Pyenogonid resembles that of Phoxichili- 
dium digitatum, Bohm. However, in many respects, it may be easily distinguished from 
this and other species of Phoxichilidium hitherto described ; for instance, by the presence 
of ovigerous legs in the female, by the presence of auxiliary claws, by the number of 
joints (10) of the ovigerous legs, &e. Like most other species of the same genus, this 
species seems only to occur in shallow water (depth 45 to 175 fathoms) not far from the 
coast. 
Phoxichilidium patagonicum, var. elegans, n. var..(Pl. XII. fig. 10). 
Diagnosis.—Like Phoxichilidium patagonicum, Hoek, only much more slender. 
Description.— 
Length of the proboscis, . . é : : : 3°5 mm. 
Total length of the body, . th ; : i ‘ ; O° 5 
Length of the abdomen, . ‘ Din te. 
Length of the leg of the third pair, . 28°53 
Length of the ovigerous leg, . eee 
A young specimen has the different thoracic segments by no means so concentrated 
or robust as is the case in the specimens of Phowichilidium patagonicum ; the lateral 
processes are much more widely separated; in general the length of the body, in com- 
parison with that of the legs and of the proboscis, is much more considerable. The oculi- 
ferous tubercle is furnished with four eyes, but the two foremost are much larger than 
the two others. The length of their legs and their joints is not very different from that of 
Phowxichilidium patagonicum ; the only difference being that the total length is compara- 
tively less. The claws and the auxiliary claws are as in Phowichilidium patagonicum. 
About the sex of this specimen I do not feel quite sure : most probably it is a young female. 
Habitat.—Station 320. February 17, 1876. Lat. 37° 17’ S., long. 53° 52’ W. 
Depth of the sea, 600 fathoms. Bottom temperature, 2:7° C. Bottom of the sea, hard 
ground. 7 
Observations.—The single specimen of this form resembles Phowichilidium pata- 
gonicum so strongly that I hesitated long whether or not I should consider it as 
specifically distinct. My study of other species, younger and older specimens, has 
convinced me that, as a rule, as the animal advances in age, its slenderness increases. 
Now, in the present case, a young specimen shows considerable slenderness, while 
the full-grown female is much more concentrated. That it is a young specimen is proved 
by the rudimentary condition of the ovigerous leg. I therefore feel inclined to consider 
this form as a variety of my Phoxichilidium patagonicum. Considering the difference 
in depth of the stations at which that species and the present form were dredged, we 
have here most probably an instance of the influence of surrounding circumstances on the 
form of an animal. 
