418 PROF. C. CHILTOH ON SOME TERRESTRIAL 



described from a single small immature specimen. I therefore give a fuller 

 description both of this and of H. australis, and place them under a new 

 genus Notoniscus. This may be described as follows : — 



NoTONiscus, nov. gen. 



Generic characters : — Body oblong, central portion moderately convex, 

 dorsal surface sculptured and bearing ridges or tubercles. Head with the 

 front triangularly produced, lateral lobes directed downwards, rather small, 

 with extremity subacute. Side plates of body lamellarly expanded, projecting 

 almost horizontally, discontiguous. Pleon not abruptly contracted, epimeral 

 plates of the three anterior segments very small or absent, those of the 

 4th and 5th segments well developed, lamellar; last segment with truncate 

 posterior margin. Eyes small, but with more than one visual element ; 

 antennules, antennae, and mouth-parts as in Trichoniscus. Legs rather short, 

 not increasing much in length posteriorly ; dactylar seta as in Triclwmsciis. 

 Uropoda with rami rather widely separated, subequal. 



This o-enus seems near to Haploplithalmns, but differs in the character of 

 the eyes and in the fact that the first three segments of the pleon have the 

 epimeral plates very small or absent. 



The genus so far as at present known is confined to New Zealand and the 

 adjacent islands and contains two species which may be distinguished as 

 follows : — 



1. Body oblong-oval, with well marked ridges or tubercles . N. helmsii. 



2. Body oval, with indistinct tubercles iV. australis. 



Notoniscus helmsii [Chilton). (PL 36. figs 1-8.) 



HaplopMhalmus helmsii, Chilton, 1901, p. 119, pi. 12. fig. 3, 

 „ „ Chilton, 1910, p. 288. 



Specific characters : — Body oblong-oval, about half as broad as long, 

 moderately convex, central portion raised somewhat abruptly above the 

 epimeral portions, which are well developed, nearly horizontal and widely 

 separated. Head with the dorsal surface bearing posteriorly two prominent 

 tubercles or short ridges projecting upwards and a little forwards, anterior 

 to these are smaller tubercles ; the front triangularly produced and somewhat 

 rounded ; lateral lobes rather small with extremities subacute, projecting 

 downwards below the raised central portion of the head. Dorsal surface of 

 the body sculptured, each segment with a short ridge or tubercle situated 

 laterally near the outer border of central portion and running obliquely 

 backwards and outwards; on the three posterior segments the tubercles 

 gradually become more distinct and pointed, projecting backwards a little 



