1314 



CRUSTACEA. 



Length, one-fifth of an inch. Colour, grass-green. 



This specimen was taken for an imperfect individual, when first 

 seen, on account of the absence of all the anterior organs between the 

 mouth and the four pairs of natatory feet, as well as that of the pos- 

 terior antennae. But beyond these particulars it has no appearance of 

 being an abortion. It cannot be young, for its size exceeds that of 

 most of the Calanidae. It has the head of a Pontella, and the abdo- 

 men of a Setella or Miracia. The buccal trunk is situated near the 

 centre of the cephalothorax below ; it is oblong conical and truncated 

 at apex, as seen under a high magnifying power; and it contains a 

 cylindrical sucker which opens at the apex. No mandibles were 

 made out, and no appendages of any kind about the sucker. The 

 shell of the venter anterior to the natatory legs is unbroken and 

 smooth, excepting the buccal prominence. 



The first segment of the cephalothorax is long and nearly linear. 

 The antennae are rather short, and are directed straight forward. 

 The appendages to first segment of abdomen are small and short, those 

 of the second long and vergiform, extending beyond the apex of 

 the abdomen. The stylets and setae are precisely as in the Pontellaa. 



Tribe II. CALIGOIDEA. 



The Caligoidea, although closely related, like the Ergasilidae, to the 

 Cyclopoidea, are more remote from that tribe in general form, and pass 

 through wider variations of structure. These species are naturally 

 grouped in three sections. One, the Argulkle, differs from the other 

 two in having no external oviferous appendages, the ova passing out 

 free direct from the oviduct : they are characterized also by having no 

 anterior antennae ; the posterior antennae two-branched, the first pair of 

 legs tubular and suctorial ; the second pair unguiculate and not pre- 

 hensile. 



In the two remaining sections there are oviferous appendages, and 

 these are alike in being simple tubes, with the ova in a single series ; 

 they have a pair of short anterior antennae ; moreover, the posterior 



