690 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



sides are proportionally ver}^ wide. The abdomen has a slight con- 

 striction on either side near the center, which indicates a division during 

 the next moult, the fourth thorax segment separating and becoming 

 free. There is a deep anal sinus at the posterior end of the abdomen, 

 on either side of which are the anal laminae. These are rather small 

 and each carries five long and stout plumose set*. 



This larva is colorless except for the pigment spots already described, 

 but is disappointingly opaque. Total length (including second anten- 

 nse), 1.1 mm. Width of the carapace, 0.4 mm. 



At the next molt these metanauplii change into a stage correspond- 

 ing to the early chalimus of the Caligina^. 



Although they differ in many 

 important particulars from the form 

 which was taken as the type of the 

 so-called Chalimus^ and although 

 they even lack a frontal filament 

 which was the essential character of 

 the chalimus, yet it is considered 

 best to retain that name for this 

 stage of development in order to 

 avoid a multiplicity of terms. Ac- 

 cordingly we designate this stage in 

 the Euryphorinfe as the chalimus 

 stage. 



The carapace (fig. 10) is oblong, 

 covering more than half the entire 

 body. It is widest at the center and 

 narrowed toward either end, the 

 posterior margin being about the 

 same width as the frotital plates. 

 The latter are thoroughly fused with 

 each other and with the carapace; 

 their anterior margins meet in a 

 rounded projection at the center 

 instead of an incision, while the lateral margins project on either side 

 far over the basal joints of the first antennte. 



The posterior margin of the carapace is nearly straight through the 

 center, with a short and narrow lobe at either corner Avhich lies closely 

 appressed to the lateral margin of the first free segment. The eyes 

 are situated in about the same relative position as during the metanau- 

 plius stage and are fully as large, with prominent spherical lenses. 

 The pigment in them is dark red in color and more abundant than in the 

 previous stage. The pigment also on the dorsal surface has increased 

 considerably in volume, and is found in the shape of spots and lines 

 scattered freely along the sides of the carapace, the free segments, and 



Fig. 9. — The second swimming leg of 



METANAUPLIUS OF ALEBION GLABER. 



