43-1 



NA TURE 



[March 7, 1S95 



later life, since by giving resistancy to the snout, it enables 

 the animal to burrow its way into the sand with such 

 astonishing facility, while the fact that it grows to the 

 front end of the body at a very early stage in the em- 

 bryonic development, long before it comes to be put to 

 this definite use, must be regarded as an instance of 

 precocious development, of which there are numerous and 

 otherwise inexplicable examples in the lield of com- 

 parative embryology."' The author regards it as probable 

 that the proximate common ancestor of Amphioxus and 

 the higher X'ertebrates was characterised by the pos- 

 session of from nine to fourteen pairs of gill-slits, 

 counting the "club-shaped gland" as representing the 

 antimere of the first primary slit. 



.-Vfter an account of the structure of the .Vscidians, these 

 animals are compared with Amphioxus, and are defined 

 as " more or less Amphioxus-like creatures which have 

 become adapted to a sessile habit of existence.'' Their 

 embryology is then described, and it is pointed out that 

 development proceeds along parallel lines in them and 

 Amphioxus '' up to a certain point, and then at the time 

 of the outgrowth of the tail in the embryo of the former, 

 and the hatching of the embryo of the latter, divergences 

 set in." The precocious formation of the larval tail in 

 Ascidians is shown to be one of the chief evidences of 

 the abbreviation which has occurred in the development 

 of this group. 



Metamerism — " that fetish of the morphologists," as 

 lirooks calls it — may, as this author points out in his 

 monograph on Salpa, " have been acquired by the 

 ancestors of the \'ertebrates after the divergence of the 

 Tunicates " ; and consequently, even if the supposed 

 metamerism of the tail in Appendicularia had not now 

 been definitely shown by Seeliger and Lefevre to be arti- 

 ficial, it could hardly have been considered of r.nccstral 

 significance. Mr. Willey recognises the secondary .-.ature 

 of the "so-called metamerism'' of the tail in this animal, 

 and is inclined to conclude that " the Appendicularix- 

 represent Ascidian larvx- which have become secondarily 

 adapted to a pelagic life, and have acquired the faculty 

 of attaining sexual maturity." We feel, however, that 

 the arguments brought forward are hardly sufficient to 

 balance those in favour of the view held by Brooks and 

 many others, that Appendicularia is the more primitive 

 type, though until the development of this form is known 

 we cannot, as .Mr. Willey points out, decide definitely 

 between these two views. 



,\s already indicated, T.ateson's grouping of ilalano- 

 glossus, Cephalodiscus, and Rhabdopleura into the divi- 

 sion Htmichordit of the group Protochordata, is accepted 

 by the author, and these forms arc described and com- 

 pared, and an account of the development of Tornaria 

 and of Kchinoderm larv.L' given. Although we fully 

 appreciate the general force of the quotation from Weis- 

 mann, given at the head of .Section \'., the perusal of the 

 foUowmg pages will not, wc fear, be convincing to every- 

 one that it applies in this particular instance. Such 

 arguments as those brought forward by .Spengel in his 

 great monograph on the Enteropneusia cannot easily be 

 put on one side, and we must make allowance for the 

 principle of parallelism in evolution.quite as much in this 

 case as in that of the Annelid theory. Nevertheless, 

 whether the llcmichord.i hypothesis proves to be true or 

 NO. 1323, VOL. 51] 



falls to the ground, it will have h.xd its value in stimulating 

 inquiry. 



So many other points of theoretical interest naturally 

 appear in considering the problem of X'ertebrate ancestry, 

 that one is tempted to discuss each as it arises. We must, 

 however, content ourselves with a bare statement of 

 certain only of these, and the conclusions at which Mr. 

 Willey has arrived with regard to them. 



It is concluded "that the ventral mouth of the craniate 

 Vertebrates is the homologue of the dorsal mouth as we 

 find it in the Protochordates, .ind that its direction of 

 evolution has been, as was so ably maintained by Balfour, 

 from the cyclostomatous to the gnathostomatous con- 

 dition." The hypophysis is supposed to have arisen " in 

 connection with a functional neuropore ; when the nfeuro- 

 pore ceased to be functional, there was no longer any 

 bond of union between its inner portion, which opened 

 into the cerebral cavity, and its outer portion, which 

 opened into the buccal cavity ; and these two portions 

 became separated by differential growth of the cerebral 

 and body. walls." Much stress — we are inclined to think 

 too much — is laid on the pre-oral lobe, which is supposed 

 to be " represented in the craniate Vertebrates by the 

 prinnandibiilar head-cavities.''' 



In conclusion, we cannot do better than quote the last 

 paragraph of Mr. Willey's useful and suggestive book, 

 which is dedicated to Prof. Lankester : — 



" For the present we may conclude that the proximate 

 ancestor of the Vertebrates was a free-swimming animal 

 intermediate in organisation between an Ascidian tad- 

 pole and .Amphioxus, possessing the dorsal mouth, hypo- 

 physis, and restricted notochord of the former ; and the 

 myotomes, cttlomic epithelium, and straight alimentary 

 canal of the latter. The ultimate or primordial ancestor 

 of the \erlcbrates would, on the contrary, be a worm- 

 like animal whose organisation was approximately on 

 a level with that of the bilateral ancestors of the 

 Echinoderms." W. N. P. 



A CYCLOPyEDIA OF NAMES. 



The Cyclopcedia of Names. Edited by Benjamin E. 



Smith, A.M. Pp. 10S5. (London : Fisher Unwin, 



1894.) 

 '"P'HE production of a pronouncing and etymological 

 -1- dictionary of proper names, encyclopxdic in its 

 scope and fulness, must have involved an immense 

 amount of care and industry. The ponderous tome 

 which represents the result of such labour comprises 



to quote from the Editor's introductory remarks — 

 " not only names in biography and geography, but also 

 names of races and tribes, mythological and legendary 

 persons and places, characters and objects in fiction, 

 stars and constellations, notable buildings and archaeo- 

 logical monuments, works of art, institutions (academies, 

 universities, societies, legislative bodies, orders, clubs, 

 lie), historical events (wars, battles, treaties, conventions, 

 &c.), sects, parties, noted streets and squares, books, 

 plays, operas, celebrated gems, vessels (warships, 

 yachts, &c.), and horses. Pseudonyms, also, which 

 have literary import.Tnce, are included. The only con- 

 dition of insertion has been that the name should be 

 one about which inform.ition would be likely to be 

 sought." 



