Euphausiidæ. 27 



process of formation, and thereby admit of being more or 

 less distinctly traced. Quite in front, just above the inser- 

 tions of the antennulæ and antennæ, a rather large and 

 well denned oval mass is seen, completely covered by the shelf- 

 like anterior expansion of the carapace (see fig. 7). This 

 mass represents the ocular plate, from which the compound 

 eyes will develop themselves. Within it, on each side, a 

 dense fascicle of fine, glistening fibres is distinctly seen, 

 being the first indication of the luminous organ found in 

 the ocular pedicles of the adult animal. In the centre of 

 the body, an opaque cellular mass is seen, which is about 

 to differentiate itself into the liver, and behind it, in the axis 

 of the body, the intestinal canal may already be clearly 

 traced, debouching ventrally near the posterior extremity of 

 the body. Finally, the heart is plainly distinguishable, lying 

 dorsally, just behind the gibbous part of the carapace. The 

 larva moves rather quickly in a somewhat jerking manner, 

 its movements being, it would seem, exclusively effected by 

 means of the antennæ. 



VIII. 

 The Calyptopis. 



The so-called Calyptopis-ioYvo. comprises several succes- 

 sive stages, all of which are charcterized by the hood-like 

 anterior expansion of the carapace, wholly covering the de- 

 veloping eyes, which only in the Furcilia-toYva become freely 

 exposed and project laterally. In the following pages, 3 

 different stages will be described; but there are several 

 intermediate stages connecting those here described. 



