SCIENTIFIC SUMMAKY. 
391 
■upon # Exotic Ornithology ” has been commenced by Dr. P. L. Sclater and 
Mr. Osbert Salvin. It is to be issued in parts, and is to consist of a series 
of coloured lithographic illustrations of new, or hitherto unfigured, birds. 
Thus, by forming a supplement to Temminck’s Planches coloriees , it will be a 
most valuable work of reference for zoologists. To the description of each of 
the species figured, the authors will endeavour to add a complete list of the 
other known species of the genus. The first series of this work will contain 
100 plates. It will be published in twelve parts, at intervals of about two 
months. Only 200 copies quarto will be published. 
The Affinities of the Dodo. — The opinion which Professor Owen has 
recently adopted in regard to the affinities of the Dodo have been in great 
part confirmed by the observations of M. Milne Edwards, the veteran French 
zoologist. In a memoir which M. Edwards laid before the Academy of 
Sciences, he stated that so far as the evidence he was able to gather from the 
examination of a set of bones lately brought from the Mauritius went, it 
showed that the Dodo belonged not to Raptorial, but to Rasorial birds. Its 
affinities are most with the Columbidge, or Pigeon family, although it must 
always be regarded as an extremely aberrant member of this group. This is 
especially shown by the formation of the sternum, or breast-bone, which is 
as unlike that of a pigeon as it is possible to conceive. — Comptes Mencius, 
April 23. 
The Locomotion of Fishes. — The views of M. Ferd. Monoyer are not without 
interest. The movement of fishes through the water takes place, he says, by 
the action of the tail, and principally of the caudal fin. When the pro- 
gression is rapid, the other fins play no part in locomotion. When the fish 
wishes to stop, it does so as an oarsman would by producing “ backwater,” 
which it effects through its pectoral fins. The other fins may be employed in 
this latter operation, but their only use is to prevent the fish turning round 
on its transverse axis. 
Disease among Oysters.- — In a report which was not long since issued by 
the Institute of Christiania, there is an account of an investigation of a 
disease among the oysters, which is said to render these mollusks highly 
dangerous to eat. The discovery was made in the course of an inquiry into 
the cause of several mysterious deaths and cases of severe indisposition, which 
the medical men were entirely unable to account for. 
How to procure Fresh-neater Polyzoa. — In a letter addressed to the editor of 
the Annals of Natural History , the Rev. W. Houghton makes some remarks 
of a highly practical value. He says that the most successful way of pro- 
curing these animals is to hunt for the characteristic statoblasts (which may, 
in most cases, be found in great numbers at the surface of the water in 
winter and spring), and to take a supply of this water, with aquatic weeds, 
and place all in a glass vessel exposed to subdued light, and kept in a mode- 
rately warm room. The statoblasts will soon germinate, and produce speci- 
mens for examination. In this way, he says, I have obtained young specimens 
of Cristatella and various specimens of Plumatella. Indeed, the naturalist 
will find it well worth his while to take at random a can of water and a hand- 
ful of freshwater weeds at any time during the open weather in winter, and 
to keep a glass vessel or two of this water and weed in his sitting-room for a 
few weeks. He will be rewarded by discovering rare forms of minute aquatic 
