102 bulletin: museum of compaeative zoology. 



the ^ixtli abdominal segment, and especiaUy of the uropods, furnish us with 

 more distinguishing marks than are generally recognized, but a^ most of these 

 details are more easily apprehended from figures, I ^v-iU dii-ect the attention of . 

 future students to these facts, believing that proportionaUy rather large and 

 very accurate drawings of the parts mentioned will be extremely useful. 



In specimens of ^gins taken on fishes, the ventral side of the thorax is 

 often, "nay almost generally, vaulted, and sometimes very considerably so 

 owing to the fact that the alimentary canal is gi-eatly distended by blood 

 sucked from the host ; another result of this swollen condition is that the seg- 

 ments of the thorax verv often become drawn out from each other. In speci- 

 mens taken on the bottom of the sea by trawl or dredge, the ventral side is not 

 vaulted, and the thoracic segments are not drawn out, it follows that such 

 specimens are comparatively shorter in proportion to their breadth than most 

 of the specimens taken on fishes, and therefore present a somewhat different 

 aspect. No specimen of the ^gins in this coUection has the ventral side 

 vaulted, and all seem to be taken on the bottom. 



Schiodte and Meinert divide the species of the genus ^ga into two groups. 

 The first of them is thus diagnosed : " Scapi antennarum infra plam vel con- 

 cav-i invicem accommodati. Lamina frontalis plana vel concava," and to this 

 group the two first described species, ^. maxima, n. sp., and J5. acw»nnafa, 

 n .p must be referred. To the other group the two authors ascribe the tol- 

 loX characters: "Scapi antennarum teretiusculi vel compressi mvicem 

 liberi^ Lamina frontalis convexa vel compresse elevata," and to this belong 

 the two other species, ^. pkbeia, n. sp., and ^. longiconns, n. sp. 



3. ^ga maxima, n. sp. 



Plate II. Fig. 2-2 c. 



Onlv one specimen, a female without marsupium. 



Head. The frontal margin rather concave on each side ; the median elon- 

 gation acute, reaching to about the middle of the interior margin of ^^ fost jomt 

 !f the antennul.. The frontal plate "lamina frontalis" _(^.n the venl^al s ^e f 

 the head), about a. long as broad, seen as much as possible from the side con- 

 !Lrablv convex, and se^en frominfront with a low and rather b-ad sublatera 

 arina and somewhat excavated in the middle. The eyes ovate the shortest 

 dSan^e between them only a little less than the basal joints of both antennul. 



''^Itmute. Reaching very little bevond the end of the peduncle of the 

 antenna, and a little beyond the anterior angle of the first thoracic segment. 

 The peduncle verv little longer than the flagellum ; its basal joint as long as 

 broad, with the upper side flatly convex, and the antero-interior angle rectan- 

 ' gular. The flageUum iT-jointed. _ 



Antenrue. Each antenna, when bent backward, nearly attains the posterior 

 marcrin of the second thoracic segment. The proportion between the peduncle 

 and°the flagellum is about that of 3 to 5 ; the flageUum 23-jointed. 



