412 SIR WILLIAM TURNER 
As the memoir of Koren and DANIELSSEN contains a description of the external 
characters with observations on the internal anatomy of the female Pennella — 
balenoptere, and is illustrated by a plate with nine figures, I have made a careful 
comparison of my specimens with their description and drawings. 
EXTERNAL CHARACTERS OF THE FEMALE. 
As the specimens in my possession, like those studied by Koren and DanteLssEn, 
were not uniform in length, | have measured the longest and the shortest in order to 
show the variation, and in the following table I have recorded their chief dimensions, 
alongside of the corresponding measurements of two of the specimens described by the 
Norwegian naturalists. 
K. & D. TURNER. 
A. B. AS B. 
Whole length of parasite : : : 320 mm. 300 294 mm. 206 
Length of head ; (3) 6 By ait 4 
Breadth of head : : 3 8 on 7 Btn 4 
Longest horn-like arm k ; : loom = 33 i 20 
Greatest thickness of arm . : : 2 1 2 301 3 
Length of thoracico-abdominal part . . 315 1 294 289 1 202 7 
Greatest thickness of same : : 6 on 6 45 on 4 
Length of pennated abdominal part . : 45 1 42 30 nn 25 
It is obvious from these measurements that the females varied considerably in 
length ; and as my shortest specimen had a pair of long ova strings attached to the 
ventral surface, it may be assumed to be adult equally with the longest. It will be 
noticed that neither of the two specimens is so long as the shortest of those recorded by 
Koren and DanigtssEN, whilst their longest specimen was 320 mm. (12% inches), — 
P. balenopterz is therefore a giant amongst the Copepoda. 
The head, both in length and breadth, slightly smaller than in their examples, had : 
a stunted, club-shaped appearance. Its colour, that of the arms and of the upper part 
of the so-called thoracic region, was brownish-yellow, whilst the lower part of that 
region and the entire extent of the abdomen was of a dark purplish hue with a shade 
of green, even after the specimens had been for several months in spirit. The head, 
arms, and upper part of the thorax were imbedded in the skin and blubber, on the 
juices in which the parasite lived. The greenish-purple-tinted part of the body floated 
in the sea-water, and was more or less in contact with the skin of the whale. Seen 
through the medium of the water, it would approximate to the colour of the skin, and 
would furnish an example of protective mimicry. 
The summit of the head was studded with numerous shallow, papilla-like tubercles ; 
they also surrounded the cleft-like opening of the mouth, which formed a deep 
mesial groove extending for a small distance on the ventral surface of the head. A 
short groove was present on the dorsal surface, which had, at its upper end, a blunt, 
hook-like tubercle at each margin, but in no instance did I see a pair of pointed, claw- 
