April io, 19 13] 



NATURE 



M7 



die to the ground in winter are rare, as are bulbous 

 plants. 



The plant associations of New Zealand, on which 

 Dr. Cockayne has written so extensively,- are of sur- 

 passing interest ; to find an equal variety a continent 

 extending to the tropics would have to be visited. 

 The northern rivers and estuaries display a man- 

 grove vegetation — a unique and unexpected occurrence 

 outside of the tropics. The lowland and montane 

 forests are of the tropical rain-forest type, and are dis- 

 tinguished by the abundance of filmy ferns, tree-ferns, 

 woody climbers, massive perching plants, deep carpets 

 of mosses and liverworts, and trees with buttress- 

 roots. The high-mountain forests are subantarctic in 

 character, and are usually dominated by the southern 

 beech (Nothofagus). Wide areas are covered by 

 shrub heath, fern heath of tall bracken, and moorland 

 with bogs, while grass-land with tussock grasses is a 

 great feature of the volcanic plateau of the North Island 

 and of the east of the South Island ; species of Poa 

 and Festuca form the chief tussocks of the lowlands 

 and lower hills, but at higher altitudes species of 

 Danthonia are dominant. 



The alpine vegetation contains, excluding lowland 

 plants which ascend to the mountains, about 550 

 species, most of which never descend below 1500 ft. 

 altitude, while some are confined to the highest eleva- 

 tions. The most beautiful of New Zealand flowers, 

 with but few exceptions, belong to this mountain 

 flora — the great white and yellow buttercups, the mar- 

 guerite-flowered celmisias, and the variously coloured 

 ourisias, eyebrights, forget-me-nots, and many more. 

 The growth-forms are often striking — cushion-plants, 

 rosette-forming plants, stiff-branched shrubs, mat- 

 forming plants, and other xerophytes are much in 

 evidence, showing the usual xerophilous leaf-char- 

 acters (hairiness, leathery structure, rigidity, needle- 

 points, &c.). 



The floras of the Kermadecs, Chatham Islands, and 

 the Subantarctic Islands (Snares, Auckland, Campbell, 

 Antipodes, Macquarie) — island groups far distant from 

 the mainland — are distinctly part of that of New- 

 Zealand. The Kermadecs contain 114 species of 

 vascular plants, only twelve of which are endemic, 

 while seventy-one belong to New Zealand proper ; 

 the largest island (Sunday Island) is covered with 

 forest in which Metro sideros villosa, a near relative 

 of the pohutakawa (M. tomentosa), is the dominant 

 tree. The Chatham Islands have 235 species, twenty- 

 nine of which are endemic, while the remainder of the 

 flora is found on the mainland. The chief plant asso- 

 ciations are forest, moor, and heath ; on the moors are 

 great thickets of the purple-flowered shrub Olearia 

 scmidentata, while there are two remarkable endemic 

 genera, Coxiella (an Umbellifer) and Myosotidium (a 

 giant forget-me-not) — both now almost extinct, unfor- 

 tunately. The Subantarctic Islands have a dense 

 vegetation consisting of 194 species, of which no 

 fewer than fiftv-two are endemic, the rest occurring 

 in New Zealand, but chiefly in the mountains. Forest 

 is found only on the Snares and the Aucklands, the 

 dominant trees beinsj an Olearia and a Metrosideros 

 respectively. Very dense scrubs occur on the Auck- 

 land and Campbell Islands, and moors are character- 

 istic of all the islands, owing to the enormous peat- 

 deposit and the frequent rain. The Cook Islands, 

 though forming a part of the dominion, have a Poly- 

 nesian flora quite distinct from that of New Zealand, 

 and are therefore not included in Dr. Cockayne's 

 notice, while, on the contrary, the flora of the Mac- 

 quarie Islands, though belonging to Tasmania, is a 

 portion of that of New Zealand. 



, the papers reviewed in Nature, \ol. lx 



NO. 2267, VOL. 91] 



The indigenous flora has been invaded by an im- 

 portant introduced element, consisting of about 540 

 species, mostly European, which has followed in the 

 wake of settlement. Dr. Cockayne points out that 

 although these aliens are in active competition with 

 the true native plants, the widespread opinion that the 

 latter are being eradicated in the struggle is quite 

 erroneous. Where the vegetation has never been dis- 

 turbed by man, there are no foreign plants at all, 

 but where man has, by farming operations, stock- 

 raising, and burning, brought about European con- 

 ditions, the indigenous plants have given way before 

 artificial meadows with their economic plants and 

 accompanying weeds. On the tussock-grass areas, 

 however, invaders and natives have met, and though 

 the original vegetation has changed, there is no reason 

 to consider the one or the other as the victor. On 

 the contrary, it appears likely that both will persist, 

 and in course of time a new flora and vegetation will 

 be evolved. F. C. 



PALEOZOIC AND OTHER ECHINOIDS.* 



THE Echinoidea afford probably greater opportuni- 

 ties for accurate phylogenetic study than any 

 other class of animals. This is due to the fact that 

 a fossil Echinoid is, when well preserved, often as 

 complete for morphological, and even ontogenetic, 

 examination as a recent specimen. No work on recent 

 Echinoids could be adequately carried out without 

 reference to the fossil forms, while any classification of 

 the group based on structures other than skeletal 

 would exclude more than half the available material. 



There could be no better proof of the absolute inter- 

 dependence of zoology and palaeontology than the 

 volume before us. The work aims primarily at a 

 revision of the known Palasozoic Echinoids, but before 

 the characters and relations of those highly specialised 

 forms can be well understood, an exhaustive general 

 survey of the morphology of the whole class is 

 necessary. Conversely, it is surprising, but none the 

 less gratifying, to find that the fullest account of 

 the lantern of a recent Echinoid yet published is in- 

 cluded in a work mainly concerned with Palaeozoic 

 types. 



In the introduction a valuable summary of the 

 methods of research (based largely on those of Hyatt) 

 is given, together with useful technical hints for the 

 preservation and development of recent and fossil 

 Echinoids. 



The first section of the work is devoted to a detailed 

 account of the comparative morphology of the class. 

 Beside the study of the lantern already mentioned, 

 three features stand out preeminently in this part. 

 Teratological and other irregularities of development 

 are here systematised for the first time, and their 

 value in the interpretation of normal conditions is 

 clearly established. The apical system, considered 

 biometrically, is found to yield important evidence of 

 the direction of evolution in species, especially among 

 the regular Echinoids. But perhaps the most note- 

 worthy conclusion reached concerns the actual com- 

 position of the test. It is shown that the only parts 

 of the Echinoid skeleton that occupy an interradial 

 position are the genital plates and the braces of the 

 lantern. Each interambulacrum is really composed of 

 two separate halves, each half having its origin in 

 the same ocular plate as the contiguous ambulacrum. 



The systematic classification contained in the second 

 section of the work is concerned chiefly with the 

 regular Echinoids. The only striking novelty is found 



1 Memoirs of the Boston Society of Natural History. Vol. vii., " Phylo- 

 geny of the Echini,' - ivith a Revision nf Palasozoic Species. By Robert T. 

 Jackson. Pp. 4<)r + 76 plates. (Boston : Printsd for the Society, 190.) 



