250 CARCINOLOGICAL STUDIES. 



slightly broader than long. The distance between the ex- 

 ternal orbital angles is however distinctly longer than the 

 length of the cephalothorax , but , as the lateral margins are 

 slightly convergent backwards, the cephalothorax appears 

 nevertheless posteriorly almost as broad as it is long. The 

 proportion of the distance between the external orbital 

 angles and the length of the carapace of the largest indi- 

 vidual (cf ) is as 6:5, in Ses. quadrata Fabr. however as 

 4:3, so that Ses. recta appears still very slightly longer 

 in proportion to the distance between the external orbital 

 angles than the other species. The upper surface is slightly 

 convex longitudinally and also somewhat declivous towards 

 the lateral and posterior margins. The usual interregional 

 grooves are very well indicated and rather deep 

 in the adult male. The upper surface is marked ante- 

 riorly with numerous transverse rugosities and 

 wrinkles that are pubescent for a part, whereas the car- 

 diac and intestinal regions are rather coarsely punc- 

 tate; the declivous lateral parts of the branchial regions , 

 finally, are provided with the usual oblique and piliferous 

 elevated lines. 



The front is slightly broader in proportion to the di- 

 stance between the external orbital angles than that of 

 Ses. quadrata and vertically deflexed. The upper 

 margin is divided into four obtuse lobes by the three usual 

 grooves which are rather deep; the two internal lo- 

 bes are slightly broader than the external; they are 

 not prominent, so that the inferior margin of the 

 front is entirely visible when the cephalothorax is looked 

 at from above. This somewhat prominent inferior margin 

 presents a rather broad, though shallow emar- 

 gination in the middle, on each side of which it is 

 very slightly sinuous ; the front is somewhat granular be- 

 tween its two margins. 



The lateral margins of the cephalothorax , which are not 

 parallel but somewhat convergent backwards, 

 are a little concave posteriorly ; they are entire, 



JJ'otes from the Leyden ]Vluseum, Vol. XIV. 



