106 DE. C. CHILTON ON THE 



If Styloniscns maffcllanicus, Dana, belongs to Trichoniscus as Stehbing * tbinks, it is 

 evident tbat tbc distinction between the Ligiidoe and the Trichoniscidge as regards the 

 antennae breaks down, for in that species the antenna may have the tlagellum with as 

 many as ten joints. Dollfus, when describing this species, had previously stated that 

 Styloniscus, Dana, is very near to Ligidlmn, and differs from it only in the uropods, which 

 want the long hairs characteristic of that genus t ; in making this statement, however, 

 he may have had in his mind also the species Styloniscns (jracilis, Dana, in which the 

 uropoda do resemble those of Ligldmm as Stcbbing has also pointed out, but it is 

 doubtful whether this species is really congeneric with S. iiuujellaniciis. 



In any case the differences betM'een the Ligiidoe and the Trichoniscidfe are not great, 

 and the existence of genera intermediate in characters is only what we may natiu'ally 

 expect. 



Dana placed Styloniscus in his sub-family Scyphacina>, liut from Stebbing's description 

 of the month-parts of ^S*. magelkmicus it is evident that that species at any rate cannot 

 come under the family Scyphacida; as I have defined it further on. 



Genus 1. Ligia, Fabricius, 1798. 



Liy'ia, Bate & Westwood^ British Sessile-Eyed Crustacea, ii. p. 44.2 (1868). 

 Ligia, Budde-Lundj Crustacea Isopoda Terrestria, p. 258 (1885). 

 Liffia, Sars, Crustacea of Norway, ii., Isopoda, p. 155 (1899). 



The generic characters are given by Sars as follows : — 



" Body regularly oval, or oblong oval, moderately convex above, with the metasome 

 not abruptly contracted ; last segment rather broad, with distinct epimeral plates. Eyes 

 large and convex. Antennulse very small, with the last joint rudimentary, uodiform. 

 Antennae rather strong and elongated. Mandibles with a ciliated lappet and numerous 

 j)enicils behind the cutting part. Maxillipeds comparatively short and stout, with the 

 terminal part rather expanded, epignath rounded. Legs gradually increasing in length 

 posteriorly, dactylus distinctly bi-unguiculate. Opercular plate of pleopoda sub- 

 branchial. Uropoda more or less elongated, basal part not produced inside, rami 

 narrow, styliform, subequal, each with a single apical spine." 



This is the only genus of the family that is represented in New Zealand, and the 

 single species, i. novce-zealamUcc, described below, agrees well with the characters of the 

 genus as just quoted from Sars. It differs, however, from the characters of the family 

 in that the two hairy bristles on the inner side of the second maxilla are wanting, and 

 the terminal part of the maxillipeds, though showing distinct evidence of five joints, has 

 the three joints preceding the terminal one united together into one plate with the 

 sutures only partially indicated. The external male organs are considerably different 

 from those of the typical species L. oceanica. In all these points L. cmstralicnsis, Dana, 

 from Australia, closely resembles L. iiovce-zealandUv, and as these pecixliarities are 

 probably shared by other species which like them are nevertheless true Ligice, it will be 

 well to slightly modify the characters of the family as laid down by Sars in order that 

 these species may be included. 



*■ i'roc. Zool. !5uc. I'JOo, p. 5{)G. t Mission du Cape Horn, Crustuces, p. 72. 



