114 DR. C. CHILTON ON THE 



powerful muscles ; the second is long, semicylindrical, narrowing and curving outwards 

 at the extremity, which hears numerous fine short setfe with points directed away from 

 the apex ; the anterior aspect shows a well-marked groove, from the sides of which near 

 the middle numerous seta) project inwards towards the groove and appear to be for the 

 purpose of holding the male organ against this appendage and keeping it firmly in its 

 place; they probably do so by interlocking with similar setie on the male organ itself, 

 though these cannot be well made out. 



The nrojwda are of the usual form, the basal portion irregularly cylindrical and some- 

 what twisted so that when detached it is difficult to get it to lie in its natural position ; 

 the outer ramus slightly narrower than the inner, but usually nearly or quite as long; it 

 bears two long setae at the apex, shorter setae being usually present on the inner branch ; 

 surface of base and rami covered with fine short setiie, giving it a roughened appearance. 



Family II. TKICHONISCID^. 



This family was established by Sars for Trichoniscus and a few other genera that had 

 previously been classed under the Ligiidse. It is closely related to that family, l)ut may 

 be recognized from it by the fact that the flagellum of the antenna has only a few joints 

 (not more than six or seven) ; the eggs are small, and contain only a few ocelli (usually 

 three), and the external male organ is single. The animals are usually small and live in 

 damp situations, none of the pleopoda being jirovided with air-cavities. 



Two genera of this family — i. e., Trichoniscus and Haplufihthalmus — are represented 

 in New Zealand. 



Genus 1. Tkichoniscus, Brandt. (PI. 12. figs. 1 & 2, and PI. 13. fig. 1.) 

 Trichoniscus, Braudt, Conspectus Crust. Oniscodorum, p. 12 (Bull. Soc. Moscou, vi. p. 174) (1833). 

 Pkilouffria, Bate & Westwood, Brit. Sess.-eyed Crust, ii. p. 454 (1868). 

 TrichoniscHS, Budde-Lund, Isopoda Tcrrestria, p. 243 (1885). 

 Trichoniscus, Sars, Crustacea of Norway, ii. p. 160 (1898). 

 Trichoniscus, Stabbing, Proc. Zool. Soc. London, 1900, p. 565 (1900). 



Generic Characters. — Body more or less oblong, attenuated behind. Cephalon rounded 

 in front, with small though distinct lateral lobes. Side-i^lates of the three posterior 

 segments of mesosome more prominent than those of the four preceding segments. 

 Metasome abruptly contracted, with the epimeral plates of the two anterior segments 

 not concealed ; last segment narrowly truncate at the tip and slightly emarginate on 

 each side. Eye small but distinct, consi.sting of only three visual elements imbedded in 

 a dark pigment. Antennulse Avith the first joint rather large and curved, last joint 

 generally longer than the second. Antennae everywhei'e clothed with small appressed 

 spikes ; flagellum much shorter than the peduncle and gradually tapering distally. Oral 

 parts considerably prolonged, giving the buccal mass a pronouncedly conical form. Left 

 mandible with two, right with only a single penicii l)ehind the cutting-part. Maxil- 

 lipeds with the distal joint of the basal part rather large, and forming at the end outside 

 a broad lamellar expansion finely ciliated at the edge ; terminal part lanceolate, with the 



