REPORT ON 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 Stomatopoda/ 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 thQ,Alimm 

 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 difier from all the other Stomatopods in the 

 possession of numerous common characteristics which are also points of resemljlance to 

 the adult Squilla, a conclusion which receives added weight from the fact that Faxon has 

 reared a young Squilla emjnisa 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 Enchthus 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, ^Wth 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, jiursuing and 

 capturing mth the greatest rapacity the Copepods and other small Crustacea which form 

 the chief part of its food. Its metamorphosis is slow, and the -n-ide distribution of most 

 of the species of Squilla is undoubtedly due to the fact that the larva is earned 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 Alimie hatch from the egg in the Alima 

 foi-m and that the Erichthoidina stage has been entirely dropped from their metamorphosis. 



' Metamorphose der Sqiiilliden, Ahhandl d. h Gmlhch. d. IFm. GbUingen, Bd. xW. pp. 111-163, Tafs. i.-viii., 

 1871. 



(ZOOL. CEALL. EXP.— PART XLV. — 18S6.) Yy H 



