GRAPSOIDEA. 347 



Planes cyaneus. 



Pedes octo postici valde compressi, articidis tribus tdtimis extus dens& 

 vittoso-ciliatis. Abdomen maris angusth triangidatum, du/plo longius 

 quam latum, 7-articidatwn, articido tertio latiore, breviore quam 

 quartus, ultimo triangidato. 



Eight posterior feet much compressed, last three joints densely ciliate 

 on outer margin. Abdomen of male narrow triangular, about twice 

 as long as broad, third segment broadest, but shorter than fourth, 

 last triangular. 



Plate 22, fig. la, animal, natural size ; b, under view ; c, exterior 

 antennae ; e, tarsus of fourth pair of legs ; /, male abdomen ; g, female 

 abdomen. 



Very abundant in the Pacific, latitude 28° north, longitude 174° 

 east; May 18, 1841. A similar animal taken in south latitude 15° 50', 

 longitude 105°, July 26, 1839. No sea-weed in these seas. 



Colour, cerulean blue. Eyes same, but paler. Length, one-half to 

 two-thirds of an inch. 



The specimen figured was from 28° north latitude. The carapax 

 is smooth and but little shining. The lateral margin has an obso- 

 lescent border. Third and fourth pairs of legs somewhat longer than 

 first or second pair. Greatest breadth of male abdomen, about half 

 the length ; of female abdomen, three-fourths the length. The an- 

 tennae are situated as shown in the figure; the exterior pair has a very 

 stout angular base. The exterior maxillipeds have the third joint 

 about half as long as second; the second is slightly arcuate within. 



The specimen obtained south of the equator was very similar to 

 the above. The description drawn up at the time does not include 

 any point of difference ; the drawing made, however, represents the 

 female abdomen very nearly orbicular, or scarcely longer than broad 

 (fig. 1 7i), which may depend on age. The length is equal to the 

 breadth, and the carapax was smooth and shining. Fig. 1 i repre- 

 sents the exterior maxillipeds. 



