SEA-FISHERIES LABORATORY. 299 



bounded by a median portion between the orbits and two 

 lateral portions. Similarly the posterior boundary 

 consists of a median portion and two lateral portions. So 

 that we may speak of these borders as the anterior, antero- 

 lateral, posterior and postero-lateral respectively. 



The Anterior Border is situated between the orbits. 

 The rostrum, which occupies the median portion of this 

 region, consists of a median and two lateral lobes. It is 

 continued ventrally as a median plate which separates the 

 two cavities in which are lodged the eye peduncles. Each 

 of the lateral lobes of the rostrum passes downwards as 

 the sujjraciliary lobe, which fuses with the anterior and 

 inner region of the second antenna (PI. Ill, fig. 20, S.I.). 

 Passing outw r ards from the rostrum the anterior border of 

 the carapace divides at each side into the supra-orbital 

 and infra-orbital portions which form the boundary of the 

 orbit. On its inner side the supra-orbital edge has the 

 prominent supra-orbital lobe which is close to the lateral 

 lobe of the rostrum. The inner boundary of the orbit is 

 fused with the outer portion of the second antenna. 



The Antero-lateral Borders form an arc of a circle the 

 centre of which is at the junction of the two outer grooves 

 bounding the epibranchial region of the carapace (see 

 below). Each antero-lateral border is divided up into 

 nine lobes by well-defined ridges. There is no definite 

 distinction between the antero-lateral border and the 

 postero-lateral border, but the latter may be said to 

 commence at the posterior end of the ninth lobe. There 

 is also a feebly marked lobe on the outer portion of the 

 postero-lateral ridge. 



The Postero-lateral Border passes backwards and 

 inwards. This border is well rounded and not so clearly 

 defined as the anterior and antero-lateral borders. 



Immediately in front of this border there is the 



