TEEEESTEIAL ISOPODA OF >;EW ZEALAND. 109 



unequal." When visiting the British Museum I found, however, that the speciniens 

 are labelled " ? Ligia notce-zealandiai, Dana," and tliat, so far as can be seen in their 

 dried and imperfect condition, they resemble my Waiwera specimens very closely, and 

 thus differ from Dana's descriptions in the other characters that I have pointed out as 

 well as in that of the rami of the uropoda. 



I have discussed this question at what will probably be tliought to be undue length, 

 but I think that full reasons should always be given before one species is regarded as 

 the synonym of another, and it is well to hesitate before venturing to dispute the 

 accuracy of Dana's descriptions. 



As this species is the largest and one of the commonest of the Terrestrial Isopoda of 

 New Zealand, and is, moreover, of a more generalized type than the others, it is deserving 

 of close attention by any who wisli to study the group, and I therefore give here a fairly 

 full accoimt of its external anatomy. I do not propose to consider its internal anatomv, 

 tliough it would no doubt repay careful consideration; indeed, I do not know that the 

 intenial anatomy of any species of the genus has yet been worked out in detail, thoun-h 

 many yeai-s ago Lereboiillet published an excellent paper on a species of the closely 

 allied genus Ligid'mm *, and Max Weber has more recently given a more minute account 

 of the anatomy of some species of the family TrlchoitiscicUc which comes close to the 

 Ligiidce f . 



Detailed Description of Ligia nov;e-zealandia^. (PI. 11.) 



The size is naturally subject to some variatioii, but all the specimens that I have seen 

 are considerably smaller than fully-grown specimens of L. oceaiiica. The following 

 measurements may be taken as about the average : — length of body 12 mm. ; greatest 

 breadth 6 mm. ; length of mesosome 7'5 mm. ; of metasome J< mm ; of antennic 10 mm. ; 

 of uropoda 5 mm. (base 2 mm., rami 3 mm.). 



The head is oval, about three times as broad as long, the anterior margin regularly 

 convex and without lateral lobes ; the eyes are large and occupy nearly the Avhole of the 

 lateral margins, their anterior and posterior sides meeting at a distinct angle; the facets 

 are small and very numerous. 



The surface of the head shows a transverse depression, interrupted in the middle, just 

 posterior to this angle of the eyes. 



The first segment of the mesosome is about as long as the head. Its epimeral portions 

 extend anteriorlv about to the middle of the lateral margins of the head, tlie suture 

 marking them off from the central portion being indistinctly marked in posterior pai't of 

 the segment only ; the posterior margin straight ; the second and third segments similar 

 but a little longer than the fii'st ; the fourth segment the widest, its posterior margin 

 slightly concave, and lateral angles a little produced backwards ; fifth, sixth, and seventh 

 segments gradually narrowing; lateral angles aciite and more and more produced 

 backwards, those of the seventh segment reaching nearly to the postero-lateral angles of 



* "Memoire siir la Ligidie de Persoon {Li(j{dium Persooni, Brandt)," Ann. d. Sciences Nat., Seconde Sc^rie, 

 tome XX. pp. ] 03-141', PI. 4 & .5. 



t " Anatomisches iiber Trichonisciden," Archiv f. Mikroskop. Anatomic, lid. xix. pp. 570-048, Tab. xxviii.-xxix. 



17* 



