294 Chronicles of Science. [April, 



other much larger, but less agile, which never leaves the sea-bottom, 

 and fitted rather to reproduce the species in a fixed locality. The 

 eggs of the two forms of Heteronereis are not at all similar; but the 

 zoosperms are identical in the two. This, however, is not the most 

 remarkable part of the case ; for it appears that these two forms of 

 Heteronereis are neither more nor less than developed forms of the 

 Nereis Dumerilii, which has also a sexual condition (consisting of 

 both males and females) as a Nereis. We have in the Nereis 

 Dumerilii, according to M. Claparede, a worm which is adult both 

 as Nereis and Heteronereis, and has probably two Heteronereidan 

 forms. An important question is whether a worm which has arrived 

 at sexual maturity as a Nereis can lose again its sexual characters, 

 and become a Heteronereis ; or whether we must consider that a 

 worm once arrived at maturity as a Nereis can never itself become a 

 Heteronereid, but only the worms which it produces are destined for 

 this condition. The question is one of importance, which must be 

 solved by study of worms kept in the aquarium. Undoubtedly we 

 have here one of the most astonishing cases of protean diversity of 

 specific form ever brought before naturalists — of a kind, indeed, totally 

 unexpected. The history of the Axolotl (chronicled by us some time 

 since) presents a sort of parallel to this case ; but it may prove that 

 the resemblance is not so close as we might at present suppose. 



M. Dumeril has shown that the Amphibian Axolotl of Mexico 

 reproduces when in its larval condition with perennial gills, as known 

 in the tropical region of Central America ; and also that in colder 

 regions losing these gills, it assumes the more perfect Salamandroid 

 form, and is reproductively active in that condition. The perenni- 

 branchiate condition may be compared to the Nereis-form, the Sala- 

 mandroid to the Heteronereis ; but it is to be observed that the dif- 

 ferences are much greater in the case of the two forms of the worm 

 than in the Amphibian : also we have no parallel to the second He- 

 teronereis form of the Nereis Dumerilii, which, by the way, is well 

 named a propos of the distinguished herpetoiogist who has made 

 known the sexual peculiarities of Siredon. 



Miscellaneous. — The eminent comparative anatomist Professor 

 Keferstein, of Gottingen, has died at the early age of thirty-seven. 

 He was an active worker, from whom much in bibliological science 

 had been already gained, and from whom much was to be expected. 



The Sars Fund. — A subscription has been started for the family 

 ot the eminent Scandinavian zoologist, Michael Sars, whose death 

 occurred last year. Whoever knows anything of marine zoology 

 knows of the work of Sars and of his eminent son, G. 0. Sars. In 

 France and Germany the subscription is progressing, and in this 

 country Mr. J. Gwyn Jeffreys has undertaken to receive contribu- 

 tions. We shall be glad to hear that the appeal to English savans 

 has been successful. 



