TEREESTRIAL ISOPODA OF NEW ZEALAND. 133 



Family V. ONISCID.E. 



In this family the molar tubercle oi' the maiulible is replaced by a tuft of stilf setie, 

 the inner lobe of the first maxilla bears only two plumose bristles ; the terminal portion 

 of the maxillipcdes is short, scarcely longer than the masticatory lobe. The uropoda 

 are more or less exposed, and the inner ramus arises anteriorly to the outer. 



The family contjiins numerous genera, of Avhich four are rej»resented in NeAV Zealand. 



Genus 1. Uniscus, Linne (1767). 



Ouiscun, Liuuicus, Syst. Nat. ii. p. 1061 (17(»7). 



Oniscus, Bute & Westwood, Brit. Sess.-eyed Crust, ii. p. 166 (1808). 



Uniscus, Budde-Luud, Isopoda Terrestria, p. 202 (1885). 



Oniscus, Sars, Crustacea of Norway, ii. p. 170 (1899). 



Generic dcucription. — "Body broad and depressed, with, the lateral parts of the 

 segments lamellarly expanded. Cephalon with well-defined lateral lobes, front im- 

 perfectly defined from the epistome. Metasome not abruptly contracted, last segment 

 considerably produced. Eyes large, sublateral. Antennula? wdth the terminal joint well 

 developed. Antenuse slender and elongated, with the flagellum comjiosed of three 

 articulations. Mandibles with numerous penicils behind the cutting-part. Legs 

 moderately slender, gradually increasing posteriorly. Opercular plates of pleopoda 

 without any air-cavities, those of the two anterior pairs deeply bilobed. Uropoda rather 

 produced, with the inner ramus originating far in front of the outer." (Sars.) 



Although there are uo actual air-cavities in the opercu.lar plates of the first and second 

 pleopoda in Oniscus, Stoller * has recently shown that in the outer portion of these plates 

 there is a structure which performs the same function of allowing the animal to breathe 

 ordinary dry air. 



1. Oniscus puxctatus, G. M. Thomson (1879). (PL 16. hg. 2.) 



07iiscus jjuuctattis, (j. M. Thomsou, Traus. N. Z. lust. xi. p. 232, pi. x a. fig. 3 (1879). 



Oniscus punctutus, Budde-Luud, Isopoda Terre.stria, p. 200 (1885). 



Oniscus jnmctatvs, Filhol, Missiou de I'ile Campbell, p. 440 (1885). 



Oniscus jjUHctutus, Thomsou & Chilton, Traus. N. Z. lust, xviii. p. 158 (1880), 



Specific description. — Body oblong-oval, rather more than twice as long as broad, 

 rather convex, whole surface covered witii short setae which in dried specimens give the 

 appearance of small scale-like markings. Cephalon with the front depressed, produced 

 slightly into an obtuse lobe ; lateral lobes small, ending subacutely. Mesosome with 

 the posterior margins of the first three segments straight and their posterior angles 

 rectangular ; lateral angles of last foiu- segments produced more and more backwards, 

 acute. Epimera of third to fifth segments of metasome well developed, narrow, ending 

 acutely ; terminal segment not much produced, triangular, much broader than long, the 

 rounded apex reaching as far as the end of the base of the uropoda and bearing a few 

 minute setae which scarcely project beyond its margin. 



* Zoologioa. llcft XXV. (^ks9y). 



20* 



