Page. — Atmospheric Carhon-dioxide and Leaf -development. 273 



The problem arose much sooner, was much easier than in the case of 

 exposed plants, and apparently was solved much earlier. I believe that 

 at the present time these advantages still show, ferns are able to extend 

 themselves recklessly — there are probably few exposed plants which rival 

 the ferns in ratio of surface to mass. 



The New Zealand kidney-fern possesses an extraordinary extension of 

 surface in proportion to its mass ; a young and vigorous New Zealand 

 cabbage-tree also shows very considerable surface : but if cut and exposed 

 to a drying wind the fern shrivels in a few minutes, the cabbage-tree scarcely 

 in a week. The fern in gaining large surface has become excessively open 

 to damage by light, by wind, and by drought ; the cabbage-tree in gaining 

 a great extension of surface has retained its power of resisting all three. 



It seems, therefore, reasonable enough to assume that even if the neces- 

 sity for increased surface arose at the same time in ferns and exposed 

 flowering-plants, the latter, faced by such difficulties, would take much 

 greater time to develop it safely. 



Art. XXXIII. — Some New Zealand and Tasmanian Arachnidse. 



By H. R. Hogg, M.A., F.Z.S. 



Communicated by Dr. C. Chilton. 



[Read before the Philosophical Institute of Canterbury, 3rd September, 1909.] 



For the phalangids and spiders now described, with one exception, I have 

 to thank Professor Benham, of Dunedin, and Dr. Chilton, of Christchurch. 



Coming from Tasmania, Stewart Island, and New Zealand, they are 

 representative of the southern fringe of the families to which they belong, 

 and I welcome this opportunity of placing them on record. 



The extension of the genus Pantopsalis to Tasmania and of Macwpsalis 

 to Stewart Island does away with the older supposition that the former 

 was pecuhar to the New Zealand regiqn and the latter to the Austrahan. 



Order ARANE^. 

 Fam. DICTYNIDiE. 

 Genus Amaurobius, Sund. 

 Amaurobius charybdis, nov. sp. 



The cephalothorax is red-brown in front, orange-brown on the thoracic 

 part, and darker orange on the cephaUc part, with a narrow median stripe 

 and side stripes quite dark brown. 



The mandibles are black-brown, the fangs black at the base, red towards 

 the point. The hp and maxillae dark red-brown. The sternum dark yellow- 

 brown, with long upstanding brown hair. 



Coxae and legs bright yellow-brown, with bands of light grey, three on 

 the femur, tibia, and metatarsus, and one on the patella. Palpi yellow, 

 with groy hairs. 



The abdomen is dark grey, mottled with small bunches of white or 

 yellow hairs. Two rather broad longitudinal yellow stripes divided by a 



