42 Transactions. — Zoology. 



hind femora have none. The fore and middle tibiae have a 

 pair of apical spines on each side, the lovi'er of which are 

 longer, but not to a great degree. The spines on the upper 

 surface of the hind tibiae are of two grades, and more or less 

 irregular. The longest spurs at the end of the hind tibiae are 

 the middle pair. The apical spines of the femora are testa- 

 ceous, deepening apically in colour to reddish-fuscous, and 

 are about half as long as the width of the genicular lobes from 

 which they spring." 



The following is a key to the species of Pleioplectron : — 



Hind femora with two minute spines below ; hind tibise 



less than five times the length of the pronotum. 



Hind tibige less than three times the length of the 



pronotum. 



Proximal joints of the antennse rather broader 



than long . . . . . . . . P. simplex. 



Proximal joints of the antennae much broader 



than long . . . . . . . . P. vectinatum. 



Hind tibise more than three times the length of the 



pronotum . . . . . . . . . . P. hudsoni. 



Hind femora unarmed below ; hind tibiae more than six 



times the length of the pronotum . . . . P. edwardsii. 



It is remarkable that our cave-wetas should belong to three 

 different endemic genera — omitting the doubtful Hemideina 

 abbreviata. Cave-wetas belonging to other genera are known 

 in North America, Europe, and Burmah, and all, as well as 

 our own, belong to the Dolichojpodina, distinguished by having 

 no foot-pads. In our genera, Macropathus is closely allied to 

 Pharmac'us, which lives on the mountains, both being known 

 at present only from the South Island ; Pachyrhaiiivia is 

 allied to Gyvinoplectron, which lives among the branches of 

 trees, both genera being known at present only from the 

 North Island ; Pleioplectron has, in the South Island, one 

 cave species and two which live among rotten w^ood, and one 

 outdoor species in the North Island. Now, we cannot 

 suppose that the immediate ancestors of our cave-wetas lived 

 in caves during their migration into New Zealand, partly 

 because of the physical impossibility of their having passed 

 from one cave to another, and partly because each is closely 

 allied to other species which do not live in caves. Macro- 

 pathxcs and Pleioidectron may have originated from a common 

 ancestor in New Zealand; but Pac/(?/?7i.amwa is more nearly 

 related to European and American forms, and its original 

 ancestors in New Zealand must have been distinct from those 

 of Pleioplectron. We must therefore, I think, conclude that 

 our first immigrant Dolichopodince did not live in caves, but 

 that some of their descendants have, like their remote northern 

 ancestors, taken to that curious mode of life. If this be true, 

 we have here a most remarkable example of the resuscitation 



