434 
POPULAR SCIENCE REVIEW, 
ZOOLOGY AND COMPARATIVE ANATOMY. 
Rate of Growth in Corals. — An interesting 1 account of the rate of growth 
of corals is given, in a letter addressed to Professor Dana by Professor 
Le Conte, and published in “ Silliman’s American Journal ” [July 1875], 
The following portion is of importance: — “ Professor Agassiz and his party 
were at Fort Jefferson, Tortugas. Dr. William L. Jones and myself had 
gone to examine a little island about eight or ten miles to the north-west. 
On returning to Fort Jefferson in a small boat, when about half way between 
the two islands, and in the still shoal water on the inside of the line of 
reefs, to our great surprise the boat suddenly grounded on the close-set 
prongs of an extensive grove of madrepores ( Madrepora cervicornis ?). On 
examining closely the trees of this grove, we found : 1. That the prongs 
were far more thickly set than is usual in this species; 2, that all the prongs 
not only of the same tree, but of all the trees of the whole grove, grow up to 
nearly the same level, which at the time examined was very near the sur- 
face ; 3, that all the prongs at that level were dead for a distance of one to 
three inches from the point. The lower limit of death seemed to be a per- 
fectly horizontal plane. The dead points rose above it to various distances 
not exceeding three inches. We rowed around the margin of this grove for 
a considerable distance, and found everywhere the same phenomena. I 
satisfied myself that the whole grove, for hundreds of acres in extent, had 
been clipped in a similar manner. On subsequent inquiry at Key West, I 
learned that the mean level of the ocean, owing probably to the prevalence 
of certain winds, was higher during one portion of the year than during the 
other. It became evident, therefore, that during the high water the living 
points of the madrepores grow upward until the descending water level 
exposes and kills them down to a certain level. With the rise of the mean 
level again new points start upward, to be again clipped at the same level 
by the descending water. The levelness, the thick setting, and the deadness 
of the points are all thus completely accounted for. It is precisely the phe- 
nomena of a clipped hedge.” 
American Zoology . — We learn from the “ Academy ” (July 24) that Drs. 
Coues and Gill are preparing a volume on the “Mammals of North 
America,” uniform with Dr. Baird’s work on the “Birds.” Mr. D. G. 
Elliott has returned to Europe with the intention of completing his long- 
planned “Monograph of the Felidae,” and we are glad to learn that he con- 
templates are-issue in quarto form of his splendid blit somewhat inaccessible 
“Monograph of the Phasianidae ” 
The Date of the Dodo and Solitaire, fyc . — M. A. Milne-Edwards has 
written a short paper on this subject in a recent number of the “ Comptes 
Rendus.” ITe says that a “manuscript entitled ‘Relation de l’ile Rod- 
rigue/ found in the Ministere de la Marine, along with evidence that it was 
published anterior to 1730 and probably not earlier than 1729, describes the 
species of the island existing at the time it was written, and among them all 
the species now known to be extinct, including the Solitaire and the extinct 
species named by A. Milne-Edwards, Rrythromachus Leguati , Ardea mega- 
cephala, Athene murivora , and Necropsittacus Rodericanus. In 1761, when the 
