Euphausiidæ. 25 



VII. 

 The Metanaupluis, 



This stage immediately succeeds the Nauplian stage, a 

 single exuviation occurring between them. The larva (see 

 figs. 6, 7) now presents a rather different appearance, 

 and already exhibits some characters that stamp it as 

 the off-spring of a malacostracan Crustacean. The 

 body of the larva, which measures about 0.60 mm. in 

 length, exhibits a somewhat irregular form, being slightly 

 compressed, with the dorsal face exceedingly convex, so as 

 to form in the middle an almost gibbous prominence. Dor- 

 sally, it is obtected by a thin, pellucid mantle (the carapace), 

 which posteriorly lies close to the sides of the body, 

 whereas anteriorly it expands to a broad, shelf -like shield 

 arching over the front part, and bordered by a number of 

 delicate radiating spinules. Behind, the body projects be- 

 yond the carapace as a short, somewhat flattened and 

 deflexed prominence, carrying, round the obtusely truncated 

 extremity, 14 unequal spines, 2 of which, occupying the 

 lateral corners, are much larger than the others (see also fig. 

 8). Of the 3 pairs of original Nauplian limbs only the 2 

 anterior still remain, the 3rd pair, the mandibular legs, 

 being wholly lost, and in their place only a small conical 

 projection is left, forming part of the mandibular body. 

 The antennulæ have preserved their structure nearly 

 unaltered, except that 2 additional bristles are found on 

 their extremities. The antennæ are also very like those in 

 the Nauplius; but the scape is now more distinctly defined 

 from the rami, and the outer of these exhibits in 



