CARPENTER—On some Pycnogonida from the Irish Coasts. 201 
for comparison, a serious drawback in such a variable genus, in 
examples of which too much stress must not be laid upon the 
presence or absence of individual spines. For example, as a rule, 
we find but three spines at the end of the dorsal aspect of the 
femur in P. levis (fig. 6), while P. spinosus has five (fig. 5) ; 
but in some examples which I would refer to P. devis, the two 
supplementary spines are present, though very small. Grube’s 
distinction by the absence of the two frontal spines is not reliable. 
They are generally absent, but not always, and are figured as 
present by Sars. The shape of the proboscis, and the number of 
cement-gland openings on the male femora seem the only constant 
distinctions, not only between P. spinosus and P. levis, but also 
between these and Dohrn’s two Mediterranean species. 
It seems to me that P. /evis has as much right to distinction 
from P. spinosus, as from P. vulgaris, or as P. charybdeus has 
from P. spinosus. The four forms are, however, so very similar in 
most structural points, that whether they are to rank as ““species”’ 
or “ varieties” must remain a matter of opinion. It seems not 
unprofitable to note their minuter details, for it is at least possible 
that the naturalists of the future may be able to observe the further 
divergence of these forms until they become undoubtedly distinct 
species. 
The genus appears, as has been said, to have arisen from 
Nymphon-like ancestors, and to be one of the most recently 
differentiated genera of the group. With this suggestion its 
distribution agrees, for while its head-quarters are the North 
Atlantic and the Mediterranean, we know that it is represented at 
scattered points in the southern hemisphere. Bohm (138) described 
a species /. meridionalis from Singapore; Haswell (14) records 
P. charybdeus from the coast of Australia, and Schimkéwitsch 
found a female of the same species in the “ Pisani”’ collections 
from the Abrochos Islands off the coast of Brazil (2). This dis- 
tribution contrasts with that of an older genus, such as Vymphon, 
which ranges uniformly over the temperate and cold seas of both 
hemispheres; it also contrasts with the truly discontinuous distribu- 
tion which would characterise a still more ancient genus which 
was on the way to extinction. We may infer, therefore, both from 
the difficulty of marking off the species of Phowichilus and from its 
