42 
S. I. Smith — Crustaceans of the Atlantic Coast. 
ences in the proportional lengths of the first and second pairs of legs, 
referred to by Stimpson, are variations due wholly to age and sex. 
The proportions given by Kroyer apply well to large males, like the 
specimen represented in his figure above referred to, while those 
given by Stimpson apply to specimens of smaller size. The following 
measurements exhibit these variations and show that they are even 
much greater in very young specimens than indicated by Stimpson. 
The proportions of the carapax in the specimen from Casco Bay ( h ) 
may have changed slightly by contraction in drying after partial 
digestion in a fish-stomach. 
a. 
b, s . 
c , $ . 
d, S . 
Length of carapax, 
XI -7mm. 
170 
27-3 
115 
Breadth of carapax, 
9-5 
15-0 
25-2 
120 
Ratio of length to breadth, 
1:0-81 
1 
: 0-88 
1: 0-92 
1: 104 
Between external angles of orbits, 
7-3 
9-6 
14-0 
49 
Length of cheliped, 
11-5 
28-5 
32 
220 
Length of anterior ambulatory leg, 
19-5 
310 
55 
300 
e, $. 
/,?• 
9, S- 
h, ?. 
i, 9. 
Length of carapax, 
22-2 
33-0 
350 
59 
64-0 
Breadth of carapax, 
21-1 
33-0 
34-3 
65 
68-5 
Ratio of length to breadth, 
1: 0-95 
1 : 1 
1 
: 0-98 
1 : MO 
1: 1-07 
Between external angles of orbits, 
12-3 
17-2 
18 
27 
Length of cheliped, 
23-0 
37-7 
36 
67 
Length of anterior ambulatory leg, 
44-3 
72 
61 
120 
125 
Upon the New England coast this 
species 
is very rare and 
appar- 
ently confined to deep water and to the off-shore banks. It is one of 
the largest arctic crabs and occasionally attains gigantic proportions. 
The extent of the ambulatory legs, in the largest individual referred 
to above, was about 800 millimeters (over two and a half feet), while 
the specimen figured by Kroyer was even somewhat larger. 
I have not been able to consult Otho Fabricius’ original descrip- 
tion of Cancer opilio, referred to by Kroyer, nor even to ascertain 
with certainty the exact date of its publication, which was very likely 
subsequent to that of Cancer opilio of J. C. Fabricius (Entomologia 
systematica, ii, p. 458, 1793), which is Inachus opilio of the same 
author (Supplementum entom. system., p. 356, 1798) and the Pisa 
armata of Milne-Ed wards. Even if priority of publication belongs 
to the species of J. C. Fabricius, I should not regard such a preoccu- 
pation in the ancient genus Cancer as sufficient reason for rejecting 
a name so well-established as opilio for the species under discussion. 
I see far less reason for restoring the old name phalangium which 
had not been in use for this species for more than three quarters of a 
