Letters, Announcements, ^c. 339 



survived, numbers of other similar forms have succumbed whose 

 remains are now found in a semifossilized state, and of these we 

 have not another vestige of record. They, like the Dodo and the 

 Solitaire, seem to have fallen victims to some enemy suddenly 

 introduced into their domain, against which they were powerless 

 to make successful resistance. The remains of these extinct 

 birds have furnished the materials for Prof. Owen's series of ex- 

 haustive memoirs on Dinornis and its allies. Dr. Buller's will 

 form a fit companion work, and thus provide us with a very com- 

 plete record of the birds of New Zealand both past and present. 

 We are promised an account of the structural peculiarities of 

 the more remarkable New-Zealand species; this will doubtless 

 be reserved for the last part. In the mean time the influence 

 these observations may have upon the sequence of the species 

 in their arrangement ought to be borne in mind. The re- 

 tention of Heteralocha in the Picarise and in the family Upupidse 

 is unfortunate ; Mr. Garrod has recently shown, in a paper 

 read before the Zoological Society, that it is certainly a member 

 of the Sturnida^ and a strictly passerine form. 



The Annual Report of the Trustees of the Museum of Com- 

 parative Zoology at Harvard College for the year 1871 con- 

 tains some matter which, though more strictly geological, is of 

 great interest to us, in the bearing it has upon the distri- 

 bution of animal life in the vicinity of Panama. Dr. G. A. 

 Maack, who accompanied the recent U. S. Darien Exploring Ex- 

 pedition, brought home with him thirty cases of geological, palse- 

 ontological, and lithological specimens; and in his Report he gives 

 a short abstract of his views of the changes that have taken 

 place in the physical aspect of the isthmus, as suggested by an 

 examination of the material he collected. The point of special 

 interest to us is the indication of two channels between the 

 oceans up to the later Tertiary times, one between the Gulf o^ 

 San Miguel and the Gulf of Uraba, the other between Panama 

 and Aspinwall. Dr. Maack also adds that he has evidence to 

 show that the Pacific Cordillera belongs to a later eruptive period, 

 and that of the Atlantic slope was in a state of tranquillity 

 when the waters of the Pacific Ocean covered the present southern 



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