TRANSACTIONS OF THli: SECTIONS. 107 



tance by another name. For in that paper the renowned malacologist just men- 

 tioned has brought to light the fact that there is another sessile and solitary Asci- 

 dian, the 3Iolgida tubulosa, which goes through no such tadpole-like stage as had 

 been supposed to be gone through by all Ascidians except the Salpoe, which is 

 never active and never puts out the activity which is so remarkable in the other 

 Ascidians, but settles down and remains sedentary immediately after it is set free 

 from the egg-capsula, neither enjoying a Wanderjahr nor possessing a chorda dor- 

 sails. We are not surprised after this that M. Lacaze-Duthiers observes that 

 " although embrj^ology may and must furnish valuable information by itself, it may 

 also, in some cases, lead us into the gravest errors." Mr. Hancock, of Newcastle- 

 upon-Tyne, has sent lis a paper upon this subject, which will be read duly and 

 duly noted by us. 



Leaving Malacology, which has not in the United Kingdom obtained the same 

 hold as yet upon the public mind that it has on the Continent, where, lUve Ento- 

 mology, there and here, it has a periodical or two devoted to the recording of the 

 discoveries of its votaries, I have much pleasure in directing attention to two short 

 papers by Siebold in the ' Zeitschiift fiir wissenschaftliche Zoologie ' (xx. 2, 1870), on 

 parthenogenesis in PoUstes yalliea v. diadema, and on pcedogenesis in the Strepsi- 

 ptera. In each of these short papers Siebold informs us that adequate room and 

 time coidd not be given them in the Innsbruck meeting held just a year ago, or in 

 the report of the meeting. It is to me a matter of difficulty to think what there 

 could have been of greater value than those papers in a section of Wissenschaftliche 

 Zoologie ; it vri.ll be to all present a matter of congratidation to learn, from the 

 venerable professor's papers, that he will shortly favour us with a new work on the 

 subject of parthenogenesis. Afresh instance of parthenogenesis in Diptera, viz. in 

 ChirononiHs, has just been put upon record in the St. Petersburg Imperial Academy's 

 Memoirs (xv. 8, January 1.3, 1870). 



The subject of the geographical distribution of the various forms of vegetable 

 and animal life over the surface of the globe, and in the various media, air, earth, 

 water, fi'esli and salt, whether deep or shallow, has always been, and will always 

 remain, one of the most interesting subsections of biology. It was the contempla- 

 tion of a simple case of geographical distribution in the Galapagos archipelago 

 which brought the author of the ' Origin of Species ' face to face with the pro- 

 blem which the title of his work embodies ; and it is impossible that sets of ana- 

 logous and of more complicated facts (many of which, be it recollected, such as 

 the combination now being effected between our own faima and ilora and those 

 of Australia and New Zealand, are patent to the observations of the least observ- 

 ing) shoidd not, since the appearance of that book, force the serious consideration 

 of the explanation it offers upon the thoughts of all who think at all. The won- 

 ders of the deep-sea faima will, I apprehend, form one, the commensalism of 

 Professor Van Beneden another, subject of discussion, and furnish an opportunity for 

 receiving instruction to all of us. Tlie one set of observations is a striking exem- 

 plification of the way in which organisms have become suited to inorganic environ- 

 ments ; the other is an all but equally striking exemplification of the way in which 

 organisms can fit and adapt themselves to each other. The current journals have*, 

 as was their duty, made us acquainted with what has been done in both of these 

 directions ; and 1 am happy to say that in the case of the deep-sea explorations, as 

 in that of parthenogenesis and spontaneous generation, a new work, giving a 

 connected and general view of the entire subject, is announced for publication. 



One instance of the large proportions of the questions which the facts of geo- 

 graphical distribution bear upon, is furnished to us in the address recently delivered 

 before the Geological Society by its president, who is also our president, and who 

 may have forgotten to refer to his own work (see ' Nature,' No. 24, 1870). Another 

 may be foimd in the demonstration which Dr. Giinther, contrary to our ordinarily 

 taught doctrines, has given us (Zool. Soc. Trans, vol. vi. pt. 7, 1868, p. 307) of the 

 partial identity of the fish-faunas of the Atlantic and Pacific coasts of Central 

 America ; many, thirdly, are furnished to us by Mr. Wallace's works passim. 

 It would be superfluous, after introducing even thus hurriedly to your notice so 



* See ' Nature,' No. 39, July 28, 1870, and Eoyal Society's Proceedings, August 1870, for 

 deep-sea explorations, and ' Academy,' September 10, 1870, for commensalism. 



