SECT. vii. CRUSTACEA. 199 



are of a singular and formidable structure. They are 

 bent outwards, and their basal joint is exceedingly 

 large, broad, and compressed; the next joint is less, with 

 a groove in its side; the third joint is a blade like 

 a scythe, whose cutting edge is furnished with long 

 pointed teeth. The Squillse are carnivorous, and, if any 

 unfortunate animal comes within their grasp, they bend 

 back the toothed edge of the first joint into the groove 

 of the second joint like a clasp-knife, and cut it in two. 

 These prehensile foot-jaws, or 'pattes ravisseurs,' are 

 like the fore-feet of the praying Mantis, and like them 

 weapons of defence. 



The genus Mysis, or Opossum Shrimps, have a long 

 straight carapace, which covers most of the thorax, and 

 folds down on each side so as to conceal the base of 

 the feet : in front it is narrow, and ends in a flattened 

 beak ; at the posterior end it is deeply scooped out. 

 The two last rings of the thorax are more or less 

 exposed ; the tail is long, almost cylindrical, tapering to 

 the end, and terminating in a swimming fin composed 

 of five plates spread like a fan. Both pairs of antennae 

 have jointed stems ending, the outer in one, the inner 

 in two very long many-jointed filaments. On the top of 

 the basal joint of the outer pair there is a very long 

 lamellar appendage, ciliated on the side next the joint. 

 Between the second and third joints of the exterior 

 antennae, Mr. Spence Bate found the organ of taste : 

 the aperture is simply covered by a membrane, as in the 

 lobster. The ears are in the last appendage of the tail. 



The Mysis has two pairs of jaw-feet differing little 

 from feet ; five pairs of thoracic feet, all thin and divided 

 into two branches, which increase in length as they are 

 nearer the tail, and are all provided with a ciliated ap- 

 pendage to adapt them for swimming. In the female, 

 broad horny plates, attached to the two last pairs of legs, 

 are bent under the body so as to form a kind of pouch, 

 destined to lodge the eggs and the young during the 



