224 
POPULAR SCIENCE REVIEW. 
interprets these facts in favour of a metamorphosis of Nereis into Hetero- 
nereis. This was the condition of the problem when Claparede resumed 
the subject, and showed conclusively (from the study of living Annelids) that 
there is a genetic relation between Nereis and Heteronereis, but he showed 
as conclusively that all Nereids do not have their Heteronereis form, as had 
been taken for granted by Ehlers, and that there is in the Annelids of this 
family a polymorphism almost without parallel in the animal kingdom. 
Taking the species which he has most carefully studied ( Nei'eis [Leontis] 
Dumerillii ) we have first a sexual form as Nereis, two sexual forms as 
Heteronereis, "and a fourth hermaphrodite form. This is alone of importance ; 
but the paper contains many more facts of interest. 
Professor Lacaze-Duthiers in the Academy . — At one of ? the meetings 
of the Academy of Sciences, Paris, the seat left vacant by the death of 
the regretted and eminent Professor Longet was given by election to M. 
Lacaze-Duthiers, Professor of Natural History at the museum. 
The American and European Bison identical. — Professor Brandt of St. 
Petersburg, in a lately published paper, renews the expression of his opinion 
in regard to the identity of the American and European Bison, both of them, 
in his view, being the lineal descendants of the fossil Bison of a now extinct 
form. The only appreciable difference between the American and European 
races, is the developed beard of the American animal, a characteristic, which, 
in view of similar differences in the manes of lions in different regions, not 
otherwise distinguishable, he considers of little importance. It may be pro- 
per, however, to say that a careful comparison of the crania of the two forms 
exhibits differences of a much more tangible character ; the relationships of 
the nasal bones not agreeing at all, and the muzzle of the American animal 
being much broader than that of its European congener. According to Mr. 
Waterhouse Hawkins also, while the tail of the American Bison has the 
hairs close pressed, with a bushy tuft at the end only, that of the European 
animal is full and rather bushy from the root, being much the same difference 
as that existing between the tails of the American Mule or Black-tailed 
Deer ( Cervus macrotis ,) and the common American eastern Virginia Deer. 
The Families of Mollusca. — The “Smithsonian Miscellaneous Collec- 
tions” contain an important review of the above by Mr. Theodore 
Gill. In view of the wide diversity of opinion among zoologists con- 
cerning the classification of Mollusca, it is not to be expected that any 
scheme that can be proposed at present will be generally adopted. Yet we 
&re constantly approximating to a true natural classification of these animals, 
thanks to the numerous anatomical investigations that have recently been 
undertaken. The author of the present work fully acknowledges the 
provisional character of the arrangement which he has adopted, and antici- 
pates many changes hereafter. In reality, some improvements made within 
the past year would doubtless have been adopted, had not the work been 
in type some six months before its actual publication. It is, nevertheless, 
the best index to the classification of the Mollusca that has been published 
hitherto. It gives in a very convenient form an arrangement in accordance 
with the views of many of the most reliable malacologists. It is probable 
that in numerous cases too many families have been admitted, or divisions 
of minor value have been allowed family rank. 
