PYCNOGONIDA. 5 
A projection beyond the insertion of the terminal claw, which occurs in some 
species, is called the Heel, a term introduced by Mr. L. J. Cole. Two other expressions 
have been adopted for purposes of convenience. In very many species, not to say 
genera, there occurs a thickening of the skin on the sides of the legs, not infrequently 
also on some of the other appendages ; this takes the form of a narrow and conspicuous 
line, usually of a reddish colour, and so it has been termed the “lateral line.” The 
other feature concerns the sete. At the extremity of most of the joints there is 
a fringe of more or less specialised sete, sometimes surrounding the joint, but 
frequently more conspicuous on the dorsal or the ventral aspect. This has been termed 
the distal fringe, a name which does not appear to be inappropriate. 
Precise measurements are invariably necessary with regard to the legs. One 
leg is generally considered to be sufficient for this purpose, and as Dr. P. P. C Hoek 
adopted the third leg of the right side for this purpose wherever possible, the same 
limb has been used here. 
PHOXICHILUS. 
This genus is readily distinguished by its slender form and the complete absence 
of chelifori and palps. The ovigers too only occur in the male, and are seven-jointed. 
Among other characters may be mentioned the presence of a “collar” between the 
cephalon and the proboscis. This, however, is deficient in the species described below. 
Numerous species have been assigned to this genus, but the difficulties of species 
discrimination is increased by the absence of two of the normal number of appendages, 
and necessitates some modification of the generic characters. No less than six species have 
been described from European seas, but their specific distinctness is open to question. 
Three others have been found in distant seas, and a fourth now deseribed is from the 
extreme south. 
PHOXICHILUS AUSTRALIS. 
(Plate L., fig. 1.) 
Specific characters :— 
Body slender, with lateral processes very widely separated and with the long legs completely 
covered with very minute stiff sete. 
Tarsus with a very prominent ventral spine, and three to five proximally on the propodus, 
which projects distinctly beyond the insertion of the terminal claw and auxiliaries. 
No distinct collar anteriorly to cephalon. 
Body slender, with the lateral processes long and very widely separated ; perfectly 
smooth to unassisted vision, but with a l-in. objective extremely minute spines can be 
detected ; segmentation very prominent and immediately behind each pair of lateral 
processes. 
The Cephalon is small, but stouter than the trunk, truncated anteriorly with the 
angles bevelled off. No collar exists as such, but a band of thin chitinous skin, 
characteristic of an articulation, occurs between the cephalon and the base of the 
proboscis. 
