470 PACIFIC SCIENCE, Vol. XXI, October 1967 
Fig. 9. Trizopagurus magnificus. Pereiopods of the glaucothoe, right side, a, Cheliped, medial view; b, 
same, lateral view; c, same, dorsal view, slightly enlarged; d, second pereiopod; e, third pereiopod; f, fourth 
pereiopod; g, fifth pereiopod. 
DISCUSSION 
Variability in the number of larval instars 
in anomuran development is now established 
as a widely occurring phenomenon. Species of 
Coenobitidae (Provenzano, 1962^), Diogenidae 
(Provenzano, 1962^ and unpublished data), 
Galatheidae (Boyd and Johnson, 1963) and 
Hippidae (Rees, 1959) have been shown to 
have a variable number of instars in larval 
development of single species. Nor is this 
flexibility in development restricted to the 
anomurans. Caridean shrimps (Provenzano and 
Dobkin, 1962; Broad, 1957), scyllaridean lob- 
sters (Robertson and Provenzano, unpublished), 
some brachyurans (Costlow, 1965; Yang and 
Provenzano, unpublished data), and at least 
one dromiid crab (Rice and Provenzano, 1966) 
have shown this pattern when reared in the 
laboratory. This phenomenon apparently re- 
sults from the independence of the moulting 
and growth processes and probably is of posi- 
tive adaptive significance. 
Although apparently there is not the uni- 
formity in general appearance among larvae of 
the family Paguridae, as was thought only a 
few years ago, all described larvae of that 
family differ in certain features from larvae of 
the Coenobitidae and Diogenidae. The pagurid 
larvae which approximate most closely the 
diogenid larvae are those of the genu Para- 
pagurus, some of which have been described by 
Dechance (1964). The larvae of one species 
(Dechance’s sp. 1, which may be P. pilosimanus 
Smith), like those of Trizopagurus magni ficus, 
have minute denticulations over at least parts 
of the body surface. 
The only diogenid larvae which have been 
described as having any sculpturing on the 
cuticle are those of Dardanus as reported by 
Dechance (1962), in which the cuticle was 
reported to have extremely small overlapping 
