1870.] Zoology. 293 



active and important work in the investigation of the fauna of that 

 part of Asia, described recently to the Zoological Society of London, 

 a new form of deer, common on the islands at the lower part of the 

 river Yangtse-Kiang, near Ching-Kiang, into the markets of which 

 city it is often brought, though it appears hitherto to have escaped 

 the observation of naturalists. This deer is distinguished by the 

 long canines and the total absence of horns in both sexes. Mr. 

 Swinhoe proposes to form a new genus for the reception of this 

 remarkable form, and gives it the name Hydropotes inermis. 



Animals presenting ttvo distinct Sexual Forms. — From the 

 time when the so-called alternation of generations became known 

 to zoologists, they have been familiar with various species of lower 

 animals which reproduce sexually under one form, and a-sexually 

 under a totally different form, the form presenting agamic repro- 

 duction being often so different from that in which sexual maturity 

 is ultimately attained, that at one time the two phases of the species 

 have been referred even to different classes of the animal kingdom. 

 The a-sexual Aphides, whose offspring become male and female 

 adults ; the Cecidomyia larvae, producing a-sexually larvae like them- 

 selves, which become eventually sexually mature flies ; the various 

 Entozoa and the Annelids of the family Syllidae, which reproduce 

 rapidly by fission, whilst at certain times individuals endowed with 

 sexual organs, and differing most markedly in their setae and other 

 characteristics are produced, — are familiar instances. Lately, by the 

 researches of Leuckart, Mecznikow, and Schneider, we have been 

 made acquainted with a nematoid worm parasitic in the frog, which 

 presents the remarkable condition, previously unparalleled in science, 

 of two sexual forms : the first, in which there are distinct males and 

 females, is a free living form ; the second, to which the eggs of this 

 bisexual generation give rise, is hermaphrodite, but at the same 

 time truly sexual in its reproduction, according to M. Schneider, in 

 which it differs from all previously recorded cases of alternation of 

 generations. M. Claus asserts the same of the Nematoid, Lejptodera 

 appendiculata ; and the Acaleph Carmarina has since been described 

 as presenting the same condition of things. M. Claparede, of Geneva, 

 amongst his other discoveries in the Bay of Naples, has brought to 

 light a most interesting case among the highest Annelids of an 

 animal presenting two distinct sexual generations. The Nereis 

 Bumerilii is the worm to which these observations refer. For some 

 time this species has been a puzzle to zoologists, and M. Malmgren 

 had already detected its relation to Heteronereis ; but the problem 

 has been fully investigated by M. Claparede. He finds that there 

 are absolutely two forms of sexually mature Heteronereis (each 

 having its own males and females, as in nearly all Polychoetous 

 Annelids) : one small and very agile, swimming on the surface of 

 the sea, and thus widely dispersing its reproductive elements ; the 



VOL. VII. x 



