140 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
A specimen of a gray lobster (Astacus gammarus) was described at a meeting of 
the Soci6te Pkilomatliique of Paris, on December 12, 1891, by M. Martin. It was 
captured at St. Vaast-la-Hougue, in a trap with several perfectly normal lobsters. 
The dorsal part of the carapace of the abnormal specimen was of a dark yellowish- 
green color, with greenish-black spots. The green color disappeared rapidly on either 
side of the dorsal median line, the yellow remaining, and passing into almost pure white 
on the sides. There was not the least trace of marbling and none of the pronounced 
blue color of the average lobster. The pleon was yellowish-green above, and yellow 
on the sides. Large irregular spots of a deep bluish-black color ornamented each 
segment, even in the dorsal parts, but without forming the usual marbled pattern. 
Martin rejects the hypothesis that this deficiency of color may be due to the 
absence of light, supposing the lobster to have lived in a dark crevice in very deep 
water, and regards this variation as adaptive, a conclusion which seems to me 
gratuitous. He says, in a note, that M. Bietrix, of Concarneau, had a white lobster, 
kept in a pond, which recovered its blue color at the next molt. A young male of 
A Ipheus saulcyi , which I once kept for several days in an aquarium, molted and lost 
completely the bright vermilion color of its claws. (94, p. 381.) 
Casual or temporary decoloration occurs in many species of Crustacea, as in Can- 
cer pagarus , of which Malard (133) says that he has met with many cases of young 
individuals living under stones in old oyster parks in the island of Tatihou, while the 
permanent absence of pigment is characteristic of certain well-known burrowing 
Crustacea Avliich live in the sand, such as Hippa, Callianassa, and Gebia. It is doubtful 
if the entire absence of pigment in such a form as Callianassa can be regarded as 
adaptive; first, because the animal burrows, and is for the most part concealed; and 
secondly, because its whiteness makes it a more conspicuous object on the sand than 
it might otherwise be. This condition may, however, be the last term iu a series of 
changes, some of which were distinctly adaptive. 
VARIATIONS IN COLOR PATTERNS. 
SPOTTED LOBSTERS. 
The spotted lobsters — “calico,” or “leopard lobsters,” as they are variously called 
by fishermen — exhibit an interesting and striking coloration, which is somewhat rare. 
They appear to be occasionally captured, however, all along the coast. An experienced 
fisherman at Rockland, Maine, said that he usually took one or two of this variety in 
the course of the season. 
There is a well-preserved spotted lobster in the museum of the Peabody Academy 
of Science, a female with hard shell, lli inches long. The whole upper part of the 
body is of a light-yellow color, with purplish blue pigments (iu the dried shell) so 
arranged as to give a spotted or marbled appearance. The light-yellow spots on the 
carapace vary much in size and shape, the largest being half an inch in diameter and 
of a slightly irregular, rounded contour. The spots are confluent at the hinder end of 
the carapace, where they form a marked yellowish area. On the sides of the carapace 
the spots are small and tend to flow together. The “tail” is marbled above with 
irregular yellow spots, in excess of the darker color. The tail-fan is yellow, beauti- 
fully mottled with reddish-purple. The appendages are spotted in the same way, light 
yellow predominating. The large claws are dark purplish-red above, with obscure 
spots; but on the under side, they are of the usual bright reddish-orange color, 
spattered with purple. 
