466 G. 0. SAKS, [t. XIII 



The metasome, or tail, exhibits the usual slender cylindrical form, and 

 is composed of 6 sharply-defined segments, successively increasing in length 

 to the penultimate one, which is the longest. Their posterior edge is some- 

 what thickened, and distinctly emarginated both on the dorsal and ventral 

 face, whereas it laterally projects as an obtuse angle. Dorsally these segments 

 have 2 longitudinal keels, which, at the posterior part of each segment, are 

 elevated to rounded crests. The last segment is considerably shorter than 

 the penultimate one, and is somewhat flattened, becoming broader at the 

 extremity, to which the uropoda and telson are articulated. 



The integuments are moderately strong, and exhibit everywhere a distinct 

 squamous structure. On the dorsal projections the squamulse are somewhat 

 projecting, giving the edges a finely serrulated appearance (see fig. 2). 



The eye, as in most other Cumacea, constitutes a single median organ 

 occupying the ocular lobe. It contains 3 distinct and highly refractive corneae, 

 one median and 2 lateral, all imbedded in a common pigmentary mass. 



The superior antennas (fig. 3), which project anteriorly from the sinus 

 between the pseudo-rostral projection and the antero-lateral corners of the 

 carapace, are rather slender, and consist each of a 3 -articulate peduncle and 

 2 flagella. The 1st joint of the peduncle, which to a great extent is hidden 

 between the lobes of the carapace, is rather thick and muscular. It carries 

 at the end exteriorly a single plumose seta, and has the inner edge finely 

 ciliated. The 2nd joint is of about the same length as the 1st, but much narrower, 

 and bears on the outer edge 5 strong bristles and a single one at the end 

 inside. The 3rd joint is still narrower, and also shorter than the 2nd, and 

 nearly linear in form. Of the flagella, the one (the exterior) is well developed, 

 about the length of the last joint of the peduncle, and consists of 3 well 

 defined articulations, the 1st of which is much the largest. It carries at the 

 end 2 band- like sensory appendages, one of which issues from the penulti- 

 mate articulation, the other from the extremely small last joint, which 

 moreover bears at the tip a short simple bristle. The inner flagellum is 

 quite rudimentary, consisting of a single very minute joint carrying at the 

 tip a few fine bristles. 



The inferior antennae (fig. 4) are completely hidden between the antero- 

 lateral corners of the carapace, and can only be seen by dissection. They 

 consist each of a small conically tapering stem, without any distinct articu- 

 lation, and tipped with a single rather large plumose seta. 



The anterior lip (fig. 5) forms a rounded flap covering over the oral 

 orifice. It is strengthened by several chitinous stripes, and has the posterior 

 edge slightly insinuated and finely ciliated. 



Bulletin N. S. IV (XXXYI) p. 302. 



