Euphausiidæ. 29 



This division is rather mobile, admitting of being turned 

 downwards nearly at right angle to the anterior division, 

 and again extended about in the axis of the latter, thereby 

 assisting in the movements of the larva. The movable 

 articulation, which produces this mobility of the posterior 

 division, is found just at the place where the carapace ends; and 

 here several muscular bundles are seen joining this part 

 both above and below. In front of this articulation there 

 is a short section of the body, which is not connected with 

 the carapace, and which represents the mesosome. It is 

 from the ventral side of this section that, in more advanced 

 stages, the true legs and the branchiæ will develop them- 

 selves; but not the slightest traces of these appendages 

 are yet visible, and still only the limbs pertaining to the 

 cephalic part of the body are present. The antennulæ do 

 not differ much in their structure from those in the Meta- 

 nauplius. On a closer examination, however, a small ter- 

 minal joint is found to be marked off, more properly represent- 

 ing the outer fiagellum, the peduncle being still inarticulate 

 The antennæ are likewise very similar to those in the 

 Metanauplius, and are still the chief locomotory organs of 

 the animal. The only difference is that the scape has di- 

 vided into 2 sharply defined segments, whereby the mobility 

 of these appendages has become considerably increased. 

 The anterior and posterior lips, as also the mandibles, are 

 more distinctly denned, and the 3 succeeding pairs of limbs 

 are now functionally developed, being engaged in conveying 

 the food to the mouth. The structure of these appendages 

 does not differ much from that found in the last Calyptopis- 

 stage, as described below. The body has become more 

 pellucid, so as to allow the inner organs to be traced more 

 distinctly, and a light red diffuse pigment has appeared in 



3 — Archiv for Math, og Naturv. B. XX. Nr. 11. 

 Trykt den 26de Juli 1898. 



