12 NATURAL SCIENCE. Jan, 
published. It isa good example of the varying “form” displayed by 
a scientific author, his present effort being as successful as his 
Anatomie Comparée was the reverse. 
Ir is interesting to remark how the skeletons of animals that we 
have always hitherto regarded as typically Old World forms of life 
are still being discovered in the Tertiary formations of North 
America. The latest announcement is that of the discovery of a 
hyzna by Professor Cope in the Pliocene formation of Texas. It is 
an animal about as large as the common spotted hyena, and is only 
known to differ from Hyena-proper in the possession of a fourth pre- 
molar in the lower jaw. It is named Borophagus diversidens (American 
Naturalist, 1892, p. 1028). With the hyena were also found two tortoises, 
one bird, one sloth, three mastodons, one peccary, three horses, one 
camel, a weasel, and a large cat. One of the horses—a true Equus— 
is remarkable for its small size, the teeth being no larger than those 
of a sheep. 
Sir Herpert Maxwe.t and Mr. J. E. Harting, the Chairman 
and Secretary respectively of the Committee appointed by the 
Board of Agriculture to investigate the plague of field voles in 
Scotland, will shortly proceed to Thessaly to examine the results of 
Professor Loeffler’s work in that region. As is well-known, the Pro- 
fessor has attempted to exterminate the Thessalian voles by placing 
in their food the germs of mouse typhus, and he claims to have been 
successful. 
THE important monograph on the development of the macrurous 
Crustacea, by Professor W. K. Brooks and Mr. F. H. Herrick, to 
which we referred some time ago (vol. i., p. 243), has lately been 
issued in vol. v. of the Memoirs of the National Academy of Sciences. 
The other memoirs in the same volume relate to physical subjects. 
We have received from Mr. Hugh Fulton a photograph of the 
beautiful little land-shell, Opisthostoma mivabile, discovered a short time 
ago by Mr. A. H. Everett in North Borneo. In ornamentation this 
minute species rivals the O. gvandispinosa, and several specimens have 
lately been obtained by Mr. Fulton. 

In the recently-issued number of the Annals of Botany, Dr. 
Schunck gives a short account of the work done on the chemistry 
of the green colouring matter of plants (chlorophyll) since the publi- 
cation of his former paper on the subject in the volume for 1889.— 
In the same journal Mr. R. A. Rolfe describes a natural hybrid 
