CETJSTACEA OF THE MEEGUI AECHIPELAGO. 109 



presents some varieties, which it will be useful to record. The 

 rich materials at my disposal have enabled me to study the slight 

 variations which, are presented by the cephalothorax and by the 

 larger hand of the male ; and I have compared them with a 

 typical specimen of this species from the Paris Museum, so tliat 

 my identification may be accepted as correct. 



Q-elasimus Dussmnieri belongs to that section of the genus 

 which is characterized by a narrow front between the eyes ; but 

 it may be distinguished from the other species of the section 

 cMefly by the shape of its cephalothorax and by the form of the 

 larger hand of the male. 



The cephalothorax of the adult male (PI. VII. fig. 2) has a 

 smooth and bright upper surface, which is very arcuate and 

 convex longitudinally, and for the shape of which I refer to my 

 figure. The front, which has been well figured by Plilgendorf 

 (I. c. fig. 1 &), is very narrow and constricted between the inser- 

 tion of the eye-peduncles, and is again enlarged a little below at 

 the rounded anterior margin, where it presents a minute, tri- 

 angular, median incision. The median furrow extends a little 

 beyond the middle of the front and is very narrow and linear ; 

 between the insertion of the eye-peduncles its breadth measures 

 a little less than a third of that of the front, so that the raised 

 margins, which border the furrow on each side, appear a little 

 broader than the furrow itself, which, is nearly equally broad along 

 its whole length. In very young males, in which the distance 

 between the external orbital angles measures 14 millim., the 

 median frontal furrow is a little broader, so that its breadth 

 somewhat surpasses that of the lateral margins. These raised 

 lateral margins of the front pass laterally into the sinuated upper 

 margin of the orbits. The latter is bordered below by an 

 accessory line at a short distance from it, running parallel to 

 the upper margin nearly from t!:e spot where the thickened 

 basal portions of the eye-peduncles pass into the slender stalk, 

 near to the point where the latter passes into the cornea. The 

 upper wall of the orbits therefore presents a long narrow stripe 

 between the upper margin and that accessory line ; this stripe 

 appears a little broader in the female than in the male, the 

 distance between the upper orbital margin and the accessory line 

 being a little shorter in the male than in the female. 



The external orbital angles are very acute and directed 



