CRUSTACEA. 517 



from the points of the antennae. Tracing this to its origin, it became 

 evident that it was produced by the rapid vibration of the foot-jaws 

 drawing in the surrounding water, and pouring it off upwards between 

 /he united antenna, as through a tube. Then, on examining these 

 organs, I perceived that the form and arrangement of their bristles did 

 indeed constitute each antennje a semi-tube, so that when the pair 

 were brought face to face the tube was complete." 



Among the numerous genera of Brachyurous Crustaceans, Grapstis 

 is distinguished by its less regularly quadrilateral form ; the body nearly 

 always compressed, and the sternal plastron but little or not at all 

 curved backwards ; the front strongly re-curved, or, rather, bent down- 

 wards ; the orbits oval-shaped and of moderate size ; the lateral edges 

 of the carapace slightly curving and trenchant ; the ocular pedicles 

 large, but short : their insertion beneath the front and the cornea 

 occupies one half of their length. 



The Hermit or Soldier Crab {Pagurus Bernhardus, Fabricius, Fig. 

 337) is, perhaps, the oddest and most curious of anomourous 

 Crustaceans. It differs from most other Crustaceans in this : that in 

 place of having the body protected by a calcareous armour, more or 

 less thick and solid, it has only a cuirass and head-piece .to protect 

 the head and breast ; all the rest of the body is invested in a soft 

 yielding skin ; and this, the vulnerable part of the hermit crab, is the 

 delicate morsel devoured by the gourmet. Nor is our somewhat 

 soft-skinned. Crustacean ignorant of the perfectly weak and defenceless 

 state of its posterior quarters. Prudence or instinct makes it seek the 

 shelter of some empty shell, of a shape and size corresponding to 

 what it needs. When it fails to find one empty, it does not hesitate 

 to attack some living mollusc, which it kills without pity or remorse, 

 and takes possession of its habitation without other form or process. 

 Once master of the shell (Fig. 345), it introduces itself, stern foremost, 

 and installs itself as in an entrenchment, where it is established so 

 firmly that it moves about with it more or less briskly, according to 

 its comparative size. 



The Soldier Crabs belong to the Anomourous family of Crus- 

 taceans, of which there are several genera, and a considerable number 

 of species, the animal economy of which has been ably commented 

 upon by Mr. Broderip. " Their backs," he says, " are placed 

 towards the arch of the turbinated shell occupied by them, and their 

 well-armed nippers and first two pairs of succeeding feet generally 

 project beyond the mouth of it. The short feet rest upon the 

 polished surface of the columella, and the outer surface of their 

 termination, especially that of the first pair, is in some species 



