ISOPODA FROM NEW ZEALAND. 419 



over the succeeding segments; on the four anterior segments there is a 

 smaller and usually less-marked ridge or tubercle internal to the one already 

 described and parallel to it ; on all the segments are slight indications of 

 other tubercles or sculpturings. Pleon not much narrower than the perteon, 

 surface smooth; first two segments small and without epimeral plates, third 

 segment with very small epimeral plates, the fourth and fifth segments with 

 epimeral plates largely developed, lamellar, the last epimeral plates reaching 

 more than half way to the end of the terminal segment ; last segment short, 

 broader than long, truncate at the apex. 



Eyes small, situated on a slightly rounded prominence above the lateral 

 lobes, containing three ocelli. Antennae short, hardly one-fourth the length 

 of the body; fourth joint of peduncle slightly expanded on outer side^ shorter 

 than the fifth which is narrowed at the base, all with appressed scales and 

 short setse, one or two longer setse on the fifth joint ; flagellum as long as 

 the fourth joint, containing 3 or 4 subequal joints and ending in a pencil of 

 long setae. Legs all short and rather stout, not visible in dorsal view, 

 apparently not showing secondary sexual characters in the male. Uropoda 

 short, base large and broad, its outer margin expanded and strongly convex ; 

 inner ramus slightly longer and more slender than the outer, arising 

 anteriorly to it but reaching as far backwards. 



Length of largest specimen, 8 mm. 



Colour. Greneral surface light brown with markings of darker brown. 



Habitat. Greymouth, one specimen [R. Helms) ; Mt. Algidus, Eakaia 

 Gorge, several specimens (T. Hall). 



This species was originally described from a single small specimen found 

 at Greymouth by Mr. R. Helms. The tubercles or ridges on its surface are 

 much less marked than in the larger specimens more recently collected b} 

 Mr. T. Hall at Mt. Algidus. It is difficult to represent accurately the 

 appearance of the dorsal surface of an animal such as this, and in my 

 original figure (1901, pi. 12. fig. 3) the ridges are less conspicuous than 

 they should be even for the' type-specimen which is there represented ; on 

 the other hand the figure which I now give, drawn for me by Mr. B. 

 Broadhead from a larger and more adult specimen, perhaps errs in the other 

 direction of making the ridges or tubercles appear somewhat too prominent. 

 Smaller specimens from Mt. Algidus closely resemble the type-specimen, 

 and I have no doubt that we are dealing with one species only, in which the 

 ridges on the dorsal surfaces become more prominent in the older specimens, 

 and, particularly in the posterior segments, project from the general surface 

 as well-marked, somewhat pointed tubercles. 



Geveral description : — The antennae (fig. 2) have already been sufficiently 

 described, the expansion of the fourth segment of the peduncle is less marked 

 in the older specimens than it was in the type-specimen ; in the type the 



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