108 BRITISH COPEPODA. 
fathoms; brackish pools near the River Stour, at 
Manningtree, Suffolk; abundant on weeds at low 
water mark, Little Cumbrae; off Portincross, Ayr- 
shire, fifteen fathoms; Scilly Islands, ten to forty 
fathoms; brackish pools at Clifden, Connemara; and 
in surface-net gatherings from Westport Bay, Mayo. 
It has also been found by the Rev. A. M. Norman 
between tide-marks at Oban; on weeds at Tobermory, 
Mull; Bressay Sound, Shetland ; and in brackish 
ee at Isle Oransa, Skye. 
The range of variation of Dactylopus tisboides, especi- 
ally as to strength and quantity of setose armature, 1s" 
very considerable. Two extreme forms, one from 
brackish water, the other from a purely marine habitat, 
are figured in the plate, but even in brackish water 
one may sometimes meet with specimens nearly as 
strongly spinous and setose as any of those from the 
open sea. Speaking broadly, however, we may say that 
there are two races or varieties of the species, charac- 
terised in one case by a robust body and strong sete, 
in the other by a slender body and delicate sete. It 
is interesting to note that, in other species, especially 
in those whose habitats—and consequently whose ~ 
manner of life—are of varied character, structural 
variations not unlike those of D. tisboides are not 
unfrequently to be found. 
The following remarks of Dr. Claus, with reference 
to a species of a closely allied genus, are of much 
interest :—‘‘ The stronger, and, on the average, the 
larger form of Harpacticus micwensis has a heavy, 
strong body—ill-bred apparently, inactive, and want- 
