Crustacea.] SUBANTARCTIC ISLANDS OF NEW ZEALAND. 649 



long as the ischium, carpus slightly expanded in its distal half, the inner margin 

 of this portion bearing about ten setae ; the dactylar claws of all the legs subequal. 

 Uropoda (fig. 13&) equal in length to the pleon ; base slightly expanded distally, as 

 long as the outer ramus, which is about two-thirds the length of the inner ; both 

 rami rather slender, and provided with small tufts of long slender setae. 



Colour, yellow, dorsal surface densely mottled with dark markings. 



Length, 3 mm. 



Hab. — Carnley Harbour, Auckland Islands, 2 fathoms (Professor W. B. Benham) ; 

 also known from Port Chalrriers, and from Lyall Bay, Wellington, New Zealand. The 

 Carnley Harbour specimen is a male, but probably immature ; it has the first pair 

 of legs less well developed than is shown in fig. 13a, which is taken from a Port 

 Chalmers specimen. I have had specimens of this species from both Port Chalmers 

 and Lyall Bay for many years, but it has hitherto remained undescribed ; in genera] 

 appearance and in the appendages it appears to approach pretty closely to Janiro. 

 maculosa, Leach, the species common in the northern seas, but it differs in having 

 the margins of the peraeon and pleon entire, and apparently the body is somewhat 

 narrower than in that species. 



Genus lais, Bovallius, 1886. 

 Distribution. — Subantarctic seas. 



lais pubescens (Dana). 



Jaera fuhescens, Dana, U.S. Expl. Exped., xiii, p. 744, pi. xlix, fig. 9, 

 1853; S. I. Smith, Bull. U.S. Nat. Mus., No. 3, p. 63, 1876. lais 

 pubescens, Stebbing, P.Z.S., 1900, p. 549, 1900 ; " Spolia Zeylanica," 

 ii, pt. V, p. 11, 1904. 



Full reference to the literature dealing with this much-described species up to 

 the year 1900 will be found in Mr. Stebbing's first paper quoted above. 



Numerous specimens were taken both at Auckland Islands and at Campbell 

 Island on Exosphaeroma gigas (Leach), and many were collected at Campbell Island 

 creeping freely on the under-surface of stones in places where the Exosphaeroma was 

 abundant. These specimens agree closely with others taken under similar circum- 

 stances at various parts of New Zealand. I have been able to compare them with 

 specimens from Falkland Islands, and I find that they agree as closely with these 

 also, as might naturally have been expected from the description given of these 

 Falkland Island specimens by Mr. Stebbing. 



This little species, Hke its host, Exosphaeroma gigas, is therefore widely distri- 

 buted round the globe in subantarctic seas, while Mr. Stebbing also records it from 

 Lake Negombo, in Ceylon, where it appears to have been associated with Sphae- 

 roma terebrans (Bate). Its connection with the host has generally been spoken of as 

 parasitic or semi-parasitic, though it perhaps would be more correctly described by 

 the word " commensal." Mr. Stebbing says of it, " Apparently the small isopod 

 makes use of the large one as a kind of floating island, affixing its eggs to it, and in 

 adult life still clinging on but doing no harm to its animated lodging." * In stating 

 that the lais attaches its eggs to the Exosphaeroma, Mr. Stebbing temporarily over- 



* P.Z.S., 1900, p. 550. 



