Land Nemer leans. ^ 



SUBANTARCTIC ISLANDS OF NEW ZEALAND. 



677 



w 



specimen from Toitoi and the first living specimen of the species found by Dendy . 

 As the coloration of this species has not before been figured, I have thought it 

 desirable to publish a drawing of it (fig. 2). The number of proboscideal nerves in 

 this specimen is 17 ; the number in the specimen from 

 Toitoi is 13. 



Punnett suggests that the known land nemerteans of 

 the world fall into two groups, of which one, including 

 Geonemertes agricola and G. chalicophora, is characterized 

 by the absence of an accessory lateral nerve, by the pos- 

 session of an excretory system, by the fact that they are 

 not striped, and that they possess a small number of 

 proboscideal nerves : G. agricola has 13-15, G. chalicophora 

 has 12. The other group includes G. palaensis (from 

 the Pelew Islands), and G. rodericana (from Rodriquez), 

 G. arhoricola, and G. graffi : all these forms possess an 

 accessory lateral nerve, but have no excretory system ; 

 they are also all striped ; and the number of proboscideal 

 nerves in them is large, varying, according to the infor- 

 mation available at the time at which Punnett's paper was 

 written, from 18 {australiensis) to 23 (graffi). With regard 

 to the two remaining species, Punnett says {loc. cit., p. 61), 

 "It is not impossible that G. novae -zealandiae may turn out 

 to belong to the same group {i.e., the latter group) when 

 more is known about it. G. australiensis resembles the 

 forms mentioned in the presence of an accessory lateral 

 nerve, but differs in having an excretory system." 



The three specimens of G. novae-zealandiae which I 

 have examined exhibited the accessory lateral nerve ; I 

 have not, however, been able to detect any traces of an 

 excretory system. But I do not attach any value, as 

 evidence, to this purely negative result. 



The presence of an accessory lateral nerve and the 

 well-marked striping point to the conclusion that G. novae-zealandiae belongs to 

 the second of Punnett's groups. The only fact which makes against this conclusion 

 is the small number (13) of proboscideal nerves in one of the specimens examined, 

 which is regarded as characteristic of the other group. 



I am of opinion that until a very much larger number of specimens of all the 

 species have been examined it is unwise to attach any systematic significance to the 

 number of proboscideal nerves in isolated specimens. 



The conclusion that the number of proboscideal nerves characteristic of Punnett's 

 two groups formed a discontinuous series, according to the evidence available at the 

 time at which Punnett's paper was written, was reached by reason of the imperfection 

 of that evidence. According to it, this number varied in the one group between 

 12 {chalicophora) and 15 {agricola), and in the other between 18 {australiensis) and 

 23 {graffi). Now we know that this number in australiensis varies between 16 and 

 19 ; and it is a noteworthy fact that the gap between the two groups should have 

 been bridged over by the species which presented the lowest number in the group 



Fig. 2. 



Geonemertea novae-zealandiae. 



Dorsal view. ( x 4.) 



