PHILOKTHRAGORISCUS. 103 



Genus 18. PHILORTHRAGORISCUS Horst, 1897. 



Syn. Dinematura Kroyer, in part. 



Female. Carapace suborbicular, width somewhat 

 exceeding the length. First thoracic segment fused 

 with the head; second and third united together, 

 forming one segment, provided with small lateral ex- 

 pansions. Fourth segment furnished with a large 

 dorsal plate, overlapping fully the half of the genital 

 segment, about as wide as the carapace and divided 

 into two suborbicular lobes by a median fissure which 

 extends nearly to the base of the plate. The genital 

 segment also furnished with a bilobed dorsal plate, 

 nearly as w T ide as that of the fourth segment, and, 

 viewed from above, almost concealing the com- 

 paratively small abdomen. Caudal rami short and 

 tolerably broad. 



Antennules two- join ted and tolerably elongated. 

 Antennae stout and armed with large hook-like terminal 

 claws. Mandibles long and slender. First maxilli- 

 peds composed of two joints and provided with three 

 terminal spines, two of them being of moderate length 

 and claw-like. Second maxillipeds stout and bearing 

 strong terminal claws. First four pairs of swimming- 

 legs biramose ; both rami of the first three pairs bi- 

 articulate. Caudal rami short. 



Wale. The carapace of the male is much larger 

 than the rest of the body; width greater than the 

 length, dorsal surface grooved as in Pandurus. Second 

 and third thoracic segments coalescent, and furnished 

 with a pair of small lateral plates. Fourth segment 

 with very small dorsal plates, which are coalescent 

 along the middle line, while the posterior margin with 

 its intermediate sinus is similar to that of the genital 

 segment in the female of Perissojms. Abdomen as in 

 the female but more exposed behind the genital seg- 

 ment. Caudal rami rather smaller than in the female. 



Antennules proportionately longer ; the antennae 

 also enlarged, their terminal claws projecting well in 



