126 Rcvieics — Dr. C. Barrois — Faune du Grh Armoricain. 



In a popular summary of liis results, contributed to a local news- 

 paper, Captain Hutton makes some interesting comments on the 

 remarkable diversity thus recognized among the extinct Struthious 

 birds of New Zealand. He considers that a plausible explanation 

 of the facts may be deduced from the known distribution of the 

 existing Cassowary. One species inhabits Australia at the present 

 day, and eight others occur on the islands from New Britain to 

 Ceram. The eight species inhabit five different islands, "and if this 

 region of the earth were to be elevated, and the islands joined 

 together, these eight species would mingle. If the region were to 

 sink once more all of them would be driven to the highest land, 

 and might be crowded into one small island. Now, we know from 

 geolog}', that New Zealand has gone through a series of changes in 

 level, similar to those just menticmed. In the Miocene period it 

 consisted of a cluster of several islands, which were elevated and 

 united in the older Pliocene, and ultimately divided into the two 

 islands we have now in the newer Pliocene. If the ancestors of 

 the Moas inhabited New Zealand during the Eocene period, they 

 must have been separated on these islands during the whole of the 

 Miocene, and mingled together again in the Pliocene. In this way — 

 i.e. by isolation — probably the genera originated, but the species 

 appear to be due to variations without isolation. As is the case with 

 most common animals, the Moas varied greatly, and, there being no 

 carnivorous mammals to hold them in check, while vegetable food 

 was abundant, natural selection did not come into play, and the 

 intermediate forms were not strictly eliminated. Under such favour- 

 able circumstances the conditions of life were easy, and the birds 

 got larger and fatter, more sluggish and more stupid. The oldest 

 known Moa is one of the smallest, and it is the smaller species which 

 are found in both islands ; from which we may infer that they were 

 the only ones in existence when the two islands were united, and 

 that the Moas since then increased in size. But the very large 

 Moas were always comparatively rare. The commonest kinds in 

 the North Island were only from two and a half to four feet high, 

 while those of the South Island were mostly from four to six feet 

 in height. The giant forms, going up twelve and thirteen feet, were 

 seldom seen." 



Such speculations are an incentive to further reseai'ch, and both 

 zoologists and geologists will anxiously await the appearance of a 

 memoir that will evidently touch problems of very wide import. 



n. — Mebioire sur la Faune du Gres Armoricain, par Charles 



Barrois. Annales de la Societe Geologique du Nord, Tome xix. 



pp. 134-237, Pis. I.-V. April, 1891. 



rpHE rocks in Brittany known as the 'gres armoricain,' have a 



Jl special intei'est from the fact that the}' are pretty well the 



lowest in France from which specifically determinable fossils have 



been obtained. M. Ijebesconte has partly described and figured 



from them, fragments of Trilobites belonging to the genera Ogijgia 



and Homalonotus and some years since the late Dr. T. Davidson^ 



1 Geol. Mag. Vol. VII. (1880), p. 342, PI. X. 



