Hawaiian Stomatopods - — ToWNSLEY 
425 
disturbed they turn around and close the 
opening with their telson, which thus serves 
as an effective protective mechanism. 
distribution: This species has been re- 
ported from Fiji and Honolulu, from rela- 
tively deep water, the only record being 50- 
120 fathoms. 
LARVAL HAWAIIAN SQUILLIDAE 
Larval stomatopods form a considerable 
part of the neritic plankton throughout the 
warmer waters of the world. They are trans- 
parent organisms which, at hatching, have 
many adult characteristics ; however, the diag- 
nostic features of the adult do not appear 
until late in development, thus making it dif- 
ficult to associate the larval forms with the 
proper adults. The first attempt to draw up 
a key to the larvae was made by Bigelow 
(1894); however, he based his key on the 
general appearance of the forms, a character- 
istic which is often very deceptive. Hansen 
(1895) made a careful study of the larvae and 
divided them into two major groups, the 
alima-type larvae of Squilla and the erichthus- 
type larvae of Lysiosquilla, Coronida, Odonto- 
dactylus^ Gomdactylus^ and Pseudosquilla^ on the 
basis of the shape of the propodus of the 
third, fourth, and fifth thoracic appendages. 
This division was thought by Hansen to em- 
phasize the relationship of the various genera 
to one another, but Kemp (1913) and Foxon 
(1932) do not believe that this is of phylo- 
genetic importance, because none of the larval 
types possesses characteristics which can be 
considered as an ancestral condition from 
which the rest of the genera developed. 
Giesbrecht (1910) has noted that in the 
Stomatopoda two types of larvae occur at 
hatching, but the differences between them 
gradually disappear through a succession of 
later stages. These two early larval types have 
been designated pseudozoea and antizoea. 
The antizoea is characterized at the time of 
hatching by biramous appendages on the first 
five thoracic somites, an abdomen which is 
usually unsegmented and lacking pleopods, 
and by later development into an erichthus 
type of larva. The pseudozoea hatches with 
only the first and second thoracic appendages, 
the second being in the form of a raptorial 
claw as in the adult, a fully segmented ab- 
domen bearing four pairs of functional pleo- 
pods; later these develop into either an erich- 
thus- or an alima-type of larva. Species of 
Lysiosquilla and Coronida hatch as antizoea, 
later developing into erichthus larvae; species 
of Gonodactylus, Odontodactylus, and Pseudo- 
squilla all hatch as pseudozoea and later de- 
velop as erichthus larvae. Species of Squilla 
hatch as pseudozoea but later develop an 
alima-type of larva. 
Foxon (1932), following the work begun 
by Hansen, attempted to bring the classifica- 
tion of the larvae into agreement with the 
divisions of the adults as presented by Kemp 
( 1913 ). In doing this he has set down the 
morphological features which serve to identi- 
fy the larvae from their earliest stages until 
the time they take on the characters observed 
in the adults. Brooks (1886), Giesbrecht 
( 1910 ), Hansen (1926), and Foxon (1932) 
have all noted that the only constant differ- 
ence between alima and erichthus larvae is 
the number of intermediate denticles between 
the submedian and the two lateral denticles 
of the telson. In the former there are always 
more than four of these denticles, whereas in 
the latter there are less than four. If one uses 
these denticles as a diagnostic character, it is 
then possible to divide the larval forms into 
the same major groups as the adults. In using 
this system of classification the larval groups 
are the same as those of the adults, the like- 
ness becoming greater at each successive molt. 
This method of classification is unques- 
tionably suitable for distinguishing the gen- 
era to which the larvae belong, but it is a 
much more difficult task to assign them to 
their proper species. In no species has an 
individual in an early larval stage been reared 
to the adult form. Individuals in later stages 
have been reared to the postlarval condition, 
but they are so delicate that laboratory con- 
