58 Transactions, — Zoology . 



EXPLANATION OF PLATE XII. 

 Fig. 1. Limncea arguta. Shell and animal. 

 Fig. 2. „ ampulla. Shell. 

 Fig. 3. „ leptosoma. Shell. 

 Fig. 4. „ tenella. Shell. 

 Fig. 5. „ pucilla. Shell. 

 Fig. 6. Planorbis corinna. Shell and animal. 

 Fig. 7. Bulinus variabilis. Shell. 

 Fig. 8. Limncea ampulla. Dentition x 470. 

 Fig. 9. ,, tomentosa. Dentition x 740. 

 Fig. 10. „ arguta. Dentition x 470. 

 Fig. 11. „ tenella. Dentition x 740. 

 Fig. 12. Bulinus mczsta. Dentition x 470. 



Art. VII. — Description of a new Species of Paper Nautilus (Argonauta 

 gracilis). By T. W. Kirk. 

 [Read before the Wellington Philosophical Society, 9th July, 1884.] 

 Plate XIII. 

 That we have in New Zealand two species of the beautiful " Paper 

 Nautilus," so called on account of the extreme delicacy of its shell, I have 

 for some years felt sure ; but although I have examined numerous speci- 

 mens, I have not until lately been able to obtain a sufficiently good series of 

 each form to justify the creation of a new species, and am now indebted to 

 Mr. C. H. Eobson of Te Mahia, who had himself noticed the difference, for 

 the loan of several examples which supply the links required to render the 

 evidence complete. 



The larger series examined, the individuals of which range from 1|— 9 

 inches across, undoubtedly belong to A. tuberculata, Shaw. The description 

 given is defective, yet a comparison of the shell with drawings by Chenu, 

 Eeeve, and other authors, is conclusive. 



I propose to amend the description as follows : — " Shell compressed, 

 sides with transverse plications which are longitudinally tuberculiferous." 

 Aperture nearly square posteriorly, margin much thickened, and the angles 

 produced outwards so as to form pointed wing-like processes, projecting 

 beyond the sides of the shell. Keels two, with compressed tubercles, white, 

 brown on the spire, where also the keel tubercles are blackish-brown. 



What I now consider to be a new species is distinguishable from the 

 foregoing at a glance. The whole shell has a more graceful and regular 

 outline, and is much more fragile looking, the aperture is narrower and 

 rounded, especially posteriorly, there is no sign whatever of wing-like 

 expansions, indeed the sides have a graceful sweep where the angle occurs 



