PARANTHURA. 163 



Genus— PARANTHURA. 



OlisJca (?). Risso. Hope. 

 Generic cJiaracter. Like Antliura, except in the structure of 

 the pleon, which has the several segments distinctly articulated 

 with each other, and carries the normal number of pleopoda. 



The animal is long, slender, and linear ; the head 

 distinct from the first segment of the body, the latter 

 consisting of seven segments, the whole being nearly 

 subequal, except the last, which is shorter than the 

 preceding. The tail is short, being about one-eighth of the 

 length of the entire animal, consisting of seven separate 

 segments, six of which support appendages. The eye^ 

 are sessile and ovate. The superior pair of antennce are 

 short, being about the length of the head, each being- 

 formed of six joints, gradually diminishing in size to 

 the last. The inferior pair is longer and much stronger 

 than the superior, and five-jointed, the large basal joint 

 being attached to the head by a short, indistinct joint ; 

 the second, third, and fourth joints gradually increase in 

 length, the fourth being not quite so long as the basal 

 joint ; the fifth joint is nearly as long as the fourth, and 

 gradually attenuated to the tip, furnished with long 

 setae, and terminated by a very minute, exarticulate 

 point. The three anterior pairs of legs (namely, the 

 two ptiirs of gnathopoda and first pair of pereiopoda) 

 are formed upon the same type, and terminate in a sub- 

 chelate hand. The four posterior pairs of legs are more 

 slender, and attached in an opposite direction to the 

 anterior pair. Each of the tail appendages (or pleopoda) 

 consists of two membranaceous plates for respiration ; 



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