123 



Prionockangon, Wood-Mason. 



Prionocrangon, Wood-Mason, Ann. Mag. Nat. Hist., Nov. 1891, p. 361 : Ortmann, Proc. Ac. Nat. Sci. Philad. 

 1895, pp. 175, 188. 



Body compressed : carapace short, with a median carina ; rostrum short : 

 integument thin. 



Eyes and eyestalks absent or represented by a pair of microscopic tubercles 

 on the anterior edge of the exposed anterior somite. 



Antennules distinctly dorsal of the antenna?. Antennular peduncle very 

 long and slender, the basal joint with a small sharp tubercle at the base of its 

 outer margin : flagella two in number, of fair length. 



Antennal scale long, acute, styliform. 



Bxopodites of the maxillipeds small, unusually slender, their flagella not 

 strongly bent inwards. 



The 1st pair of thoracic legs, though the stoutest of all, are not very 

 massive : they are subchelate, the edge against which the dactylus folds being 

 more longitudinal than oblique. 



The 2nd-5th legs are monodactylous, the dactyli being minute : the 3rd 

 pair are very slender, the others are stout. 



The endopodites of the first 5 abdominal appendages are almost rudimentary. 

 The gills are five on either side, being pleurobranchiae and being attached 

 to the last 5 thoracic somites. 



73. Prionocrangon ommatosteres, Wood-Mason. 



Prionocrangon ommatosteres, Wood-Mason, Ann. Mag. Nat. Hist., Nov. 1891, p. 362 : Alcock and Anderson, 

 J. A. S. B. Vol. LXIII. 1894, pt. 2, p. 152 : Ortmann, Proc. Ac. Nat. Sci. Philad. 1895, p. 189. 

 Illustrations of the Zoology of the Investigator, Crustacea, Plate IX. Fig. 4. 



Carapace from a third to two-sevenths the total length, its median carina, 

 which extends to within a short distance of the posterior border, 6 or 7-toothed. 



Though the eyes and eyestalks are wanting, there is a fairly well pronounced 

 orbital notch, defined externally by a tooth : the post-antennal spine reaches 

 further forwards than the tip of the rostrum. The rostrum is short, sharp, and 

 ascendant. 



Abdomen smooth : telson blunt-pointed, hardly as long as the 6th abdominal 

 somite. 



Antennular peduncle more than three-fourths the length of the carapace, 

 measured in the middle line, by far the greater part of its extent being formed 

 by the first joint : the flagella, which are slender and of nearly equal length, 

 are as long as the long first joint. 



The styliform antennal scale is half as long as the carapace. 



