128 CRUSTACEANS OF TUK 



marked mesially as the usual semicircular groove, but tliere 

 is no trace at all of the lateral portions, the gastric 

 region being confluent with the branchial one. The cardiac 

 region is likewise not defined, the brauchio-cardiac grooves 

 are quite indistinct. The small urogastric areolets that are 

 not contiguous, are only defined by minute puncta, but 

 by no grooves and the depression between the anterior 

 and the posterior branchial region is very faint. The nar- 

 row linear mesogastric furrow is continued on the front 

 and also backwards, almost to the middle of the gastric 

 region but does not bifurcate. The epigastric lobes are 

 faintly marked; they are separated anteriorly by a trans- 

 verse groove from the front and each lobe is bounded 

 posteriorly by a slightly oblique ridge, in front of which 

 one observes a row of fine puncta. These two ridges (Fig. 

 15") meet together at the mesogastric furrow and they are 

 a little farther distant from the anterior groove than the 

 latter from the free border of the front. In the smaller 

 specimen the two ridges are indistinct, the transverse rows 

 of minute puncta being only developed. On each side of 

 the epigastric lobes one observes a transverse ridge, 

 that runs somewhat obliquely forward and outward ; 

 these two ridges that are characteristic of our species and 

 that are equally distinct in both individuals, so that the 

 specific name is derived from them, are apparently the 

 rudimentary traces of the post-frontal ridge. They reach 

 laterally as far as the eye-peduncles and are nearly straight. 

 The distance between the outer orbital angles that are 

 not at all prominent, measures about two thirds the 

 greatest width of the cephalothorax, the proportion be- 

 tween both being as 5:3. The free border of the front 

 (Figs. 15*^ and 15*) that is straight, not emarginate in the 

 middle, measures one fourth the greatest breadth of the 

 cephalothorax. It makes angles of 135° with the upper margins 

 of the orbits, about as in Pot. Dehaani, so that the shape 

 of the front is nearly the same in both species, the front 

 being distinctly broader above than at the free border. 



Notes from the Ley den Museum, Vol. XXI. 



