336 SYNOPTIC COLLECTION. 



All the appendages of this Stomatopod are adaptive 

 even at this early age, and Brooks 1 has shown that dur- 

 ing the long larval life the larvae have undergone many 

 secondary modifications which have no reference to the 

 life of the adult and are therefore unrepresented in the 

 adult organism. Indeed, the larvae differ among them- 

 selves, says this investigator, "more than the adults, thus 

 reversing the general rule that larvae are less specialized 

 and exhibit clearer evidence of genetic relationship than 

 mature animals." At the same time Brooks has shown 

 that the changes which convert the larva into the adult 

 are very gradual, and that the development may be 

 regarded as the simplest expression of the extremely com- 

 plicated metamorphosis of the specialized Crustacea. 

 Inasmuch as the changes are slight compared with those 

 of most stalk-eyed Crustacea, 2 we have a sufficient reason 

 for placing Squilla among the more generalized Malacos- 

 traca. 



When fully grown, Squilla (No. 827, ,5. nepa Latr.) 

 excavates holes in the sand, and one species, Lysiosquilla 

 excavatrix, buries itself with the exception of the tips of its 

 eye-stalks while waiting for its prey. The body of Squilla, 

 like that of the larva, is long and made up largely of dis- 

 tinct and movable segments. When viewed from the 

 dorsal side (No. 827, specimen on the left) only a few 

 pairs of jointed appendages are seen, but a ventral view 

 (No. 827, specimen on the right) exposes a large number 

 of these paired organs extending from one end of the 

 body to the other. 



The preparation (No. 828) shows more plainly the 

 parts that make up the external skeleton. There are 

 seven distinct segments in the posterior or abdominal 



1 Chall. Rep., Zool., XVI, part 45, 1886, p. 4. 



2 Brooks, Johns Hopkins Univ., Stud. Biol. Lab., I. In this vol- 

 ume is included Chesapeake Zool. Lab. Scientific Results of season 

 of 1878, p. 152. 



