2 THE VOYAGE OF H.M.S. CHALLENGER. 



larval life, during which they swim at the surface and are swept to great distances 

 by the oceanic currents. 



There are, however, many species which are known from only a single restricted 

 locality, and almost one-fourth of the species which have been described are represented 

 by solitary specimens, and there is therefore every reason to believe that many species, 

 and possibly many genera, are still unknown, and that our knowledge of the group is 

 very incomplete. They are extremely active in their movements and retiring in their 

 habits, and they may remain undiscovered in a locality where they are abundant. A few 

 species are recorded as dwelling in crevices in coral reefs, but most of them are burrowing 

 animals. The living animals which form their prey are captured in the long raptorial 

 claws, and some species, like Squilla empusa, often venture to a great distance from their 

 burrows in their pursuit of prey, and are frequently captured in nets and trawls, although 

 others, such as Lijsiosquilla excavatiix, are the Myrmeleons of the ocean, lying in wait 

 for their prey, covered with sand, with only the tips of their eyes exposed, at the mouths 

 of their very deep burrows, to the bottoms of which they dart at the least alarm. At 

 Beaufort, N.C., Lysiosquilla excavatrix is so abundant that the mouths of several burrows 

 may often be found in shallow water in a square yard of the bottom, yet during the six 

 summers I have passed there, I have obtained only one adult specimen which was 

 captured outside its burrow, and only one which was obtained by digging. It was not 

 until I devised the plan of holding near the mouth of the burrow with one hand a piece 

 of bait, such as a small fish or a crushed crab, while the other hand was held ready with 

 a trowel to cut oif the retreat to the bottom of the burrow, that I was able to procure 

 them in abundance, and the movements of this species are so very rapid that most of the 

 specimens were so near escaping that they were cut in two when the trowel was plunged 

 into the ground. 



The Challenger collection of adults is a very small one, consisting of only fifteen 

 species, but eight of them are new, while two of the others, Squilla fasciata and Proto- 

 squilla (Gonodactylus) guerinii, have been very inadequately described from single 

 specimens. The importance of the collection must not, however, be estimated by its 

 size, for it throws light upon many interesting problems, and furnishes the material for 

 a more exhaustive and satisfactory discussion of the phylogenetic relationship and the 

 natural classification of the various genera and species than has been possible hitherto. 



The collection of pelagic Stomatopod larvae is very rich, and it has yielded the 

 material for tracing the history of several of the larval types, and also for estabhshing, 

 in every genus except one, the connection between the adults and their larval types. 



The larval history of the Stomatopoda is one of the most puzzling problems 

 in morphology, and most of our knowledge of the subject is derived from Claus's well- 

 known memoir.^ 



' Die Metamorphose der Squilliden, Abhandl. d. k. GeselUch. d. Wi^s. Gottingm, Bd. xvL pp. 1-55, pis. i.-viii., 1871. 



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