216 CRUSTACEA. 



are still more rudimentary. But the most singularly 

 altered portion is the fin at the end of the tail, which 

 here becomes transformed into a kind of holding- 

 apparatus, by which the creature retains a firm 

 grasp upon the interior of its residence. 



SECOND ORDER OF CRUSTACEANS. 

 STOMAPODA.* 



The Stomapoda (Mouth-footed Crustaceans) are so 

 called, because their feet are collected in the imme- 

 diate vicinity of the mouth. In this order the prin- 

 cipal organ of locomotion is the tail, which broadly 

 spread, and armed with a beautiful expansion at its 

 extremity, carries beneath it the false feet, here 

 developed into five pairs of broad leaf-like organs, 

 which constitute the instruments of respiration. The 

 integuments of the Stomapodes are thin and almost 

 membranous. * 



The Mantis Shrimp (Squilla mantis) is remarkable 

 on account of the strange resemblance between its 

 fore-legs and those of the insect Mantis, described in 

 a preceding chapter. Its carapace covers only the 

 anterior half of the thorax; the hinder portion 

 being formed of rings like those of the abdomen. 

 It is provided with enormous claws, terminating in a 

 sharp hook ; the last joint furnished with six sharp 

 projecting spines, and the preceding joint with three, 

 and so hollowed as to render this claw a most efficient 

 instrument of prehension. The other foot-jaws, and 

 the three anterior pairs of thoracic members, share 

 in this conformation, and serve to hold the prey 

 against the mouth. The three posterior pairs of legs, 

 which are attached to the annulated portion of the 

 thorax, are furnished with a brush instead of a hook 

 at their extremities, and more resemble the abdominal 



* crro^a, stoma, the mouth ; irovs, pous, a foot. 



