24 THE VOYAGE OF H.M.S. CHALLENGER. 



side is very distinct and rather deep, and the antero-lateral corners of the carapace are 

 produced to a sharp point. The inferior edges of the carapace are evenly curved, and in 

 the greater part of their length strongly serrate. The ocular lobe (see figs. 3, 4) is rather 

 large and oval in form, almost reaching to the tip of the pseudorostral projection. It is 

 armed on the anterior part with two small anteriorly directed denticles, and seems to 

 exhibit pretty well developed visual elements. 



The exposed part of the trunk is composed of five well-defined segments, the anterior 

 of which is the shortest, the second the largest. On all the segments the lateral parts 

 form broad laminar epimera, slightly projecting at the sides (see fig. 2). 



The tail is only very slightly longer than the anterior division of the body, and of 

 the usual slender cylindrical form. Of its segments the penultimate is by far the longest. 

 The last segment (see fig. 5) is rather short, and has the posterior edge produced in the 

 middle to a short triangular plate arching over the anal orifice, but not defined from the 

 segment by any suture. On each side of this plate is found a row of five slender 

 spines increasing in length posteriorly. 



All the integuments are rather thin, only very slightly indurated, and exhibiting 

 under the microscope a squamous structure. The colour of the specimen preserved in 

 spirit is whitish, with a few stellate pigmentary patches, especially distinct on the 

 carapace. 



The antennulse (fig. 4, a') are of moderate size, and have one of the flagella very short, 

 and uniarticulate, the other triarticulate, and bearing at the tip two ribbon-like sensory 

 appendages. 



The antennse (fig. 4, ct'^) are very small and biarticulate, their outer part projecting 

 from the bottom of the anterior notch of the carapace. 



The terminal plate of the exopodite of the maxillipeds projecting in front of the 

 carapace (see figs. 3, 4, x) is very thin and quite membranous, being drawn out to a 

 narrow, somewhat tubular lappet. 



The first pair of legs (see fig. 1) are rather slender, though not nearly so elongate 

 as in the tj^ical species; they only slightly exceed in length the carapace, and have the 

 three last joints nearly uniform in size. 



The remaining pairs of legs do not seem to difi"er materially in structure from those 

 of Vaunthompsonia cristata, and as in that form only the two last pairs are simple, 

 whereas the two preceding pairs are provided with well-developed natatory exopodites 

 of similar structure to those on the first pair. The second pair are only slightly shorter 

 than the first, and composed of but six joints, the ischial joint not being distinctly 

 defined. 



The uropoda (see fig. 5) do not attain the length of the two posterior caudal segments 

 taken together, and exhibit a comparatively coarser structure than in the typical species. 

 The scape is rather thick, and armed along the inner edge with about ten strong spines. 



