REPORT OX THE STOMATOPODA. 
81 
The Alima Larva and the Metamorphosis of Squilla. 
Although, as Claus has well shown in his classical monograph on the metamorphosis 
of the Stomatopocla, 1 the Alima larva is connected with the Erichthus larva by so many 
intermediate forms that it is difficult to draw an absolute line between them, it is never- 
theless true that the Alima is more different from the Erichthus than any of the various 
modifications of the latter type are from each other, and in the description and discussion 
of the Alima larva which follows, I shall give my reasons for believing that all the Alimse 
are the larvae of adults which belong to the genus Squilla, and that all the species of 
this genus pass through an Alima stage, while all the other Stomatopods pass through 
their larval life as Erichthi. The Alima larva is undoubtedly a modified Erichthus, and 
some species deviate much more widely than others from the Erichthus type, but the 
group is on the whole sharply defined, and the rich supply of Alima larvae brought home 
by the Challenger furnishes us with a very complete series of stages in the growth and 
development of several species of Alima, and thus shews that the history of all of them 
is essentially the same, and that they differ from all the other Stomatopods in the 
possession of numerous common characteristics which are also points of resemblance to 
the adult Squilla, a conclusion which receives added weight from the fact that Faxon has 
reared a young Squilla empusa from an Alima larva. 
The complete history of the Alima which is furnished by the Challenger material is 
all the more valuable since Claus, who has given us, in his paper above quoted, a very 
complete history of the young stages of the Erichthus larva in all its more important 
modifications, had access to much more scanty material for studying the Alima. It is 
true that he gives figures and descriptions of many forms, but they are all well advanced 
and have the same number of somites and appendages as the adult Stomatopoda, and the 
fact that the Challenger collection contains consecutive series of several species of Alima 
from a very early stage up to the mature larva, with unmistakable characteristics of the 
genus Squilla, is therefore of great scientific interest. 
The fully grown Alima is usually much larger than any of the Erichthi, and among 
the largest known pelagic larvae. It leads an active swimming life, pursuing and 
capturing with the greatest rapacity the Copepods and other small Crustacea which form 
the chief part of its food. Its metamorphosis is slow, and the wide distribution of most 
of the species of Squilla is undoubtedly due to the fact that the larva is carried to distant 
localities by the winds and currents, but notwithstanding the great size, often 2 inches or 
more, which is attained by the fully-grown larva, the young Alima, even of the largest 
species, is very minute, and it is probable that all Alimse hatch from the egg in the Alima 
form and that the Erichtlioidina stage has been entirely dropped from their metamorphosis. 
1 Metamorphose cler Squilliden, Abliandl. cl. k. Gesellsch. cl. rViss. Gottingen, Bd. xvi. pp. 111-163, Tafs. i.-viii., 
1871. 
(ZOOL. CHALL. EXP. — PART XLV. — 1886.) Yy 11 
