I50 



lYA TURE 



[Junk 



1895 



times. Whilst iti this respect the work, for a text-book, 

 suffers unavoidably from too much of the "study," it. on 

 the other hand, would have been better if an extension of 

 time had been allowed the author in which to weld his 

 mass of interesting and valuable material into a more 

 homogeneous whole. 



The method of treatment of the subject, differing as it 

 does in many respects from that of the ordinan,- hand- 

 book, will best be jjrathered from a brief recapitulation of 

 the order in which the main points are taken. 



I'rcfi.xed is a scheme of the classification adopted ; and 

 concerning this it will be more convenient to speak later 

 on. The opening pages are devoted to a brief intro- 

 ductory statement defining the relationship of the MoUusca 

 to the rest of the animal kingdom, and sketching their 

 classification so far as the principal groups are concerned. 

 Only one phylogcnetic table is submitted, and that, un- 

 fortunately, the misleading one dividing the Molluscainto 

 the utterly unnatural groups of (.lossophora and .\glossa. 

 On the other hand, .Mr. Cooke is cordially to be con- 

 gratulated on refusing to have aught to do with that 

 mythical monster, the "archi-" or "schematic-mollusc."' 

 .\ discussion on the origin of ihe land and fresh-water 



KiG. 3 — Three Plages in ihc growth of Ptcrocera nigosa, .Sow, 



mollusca follows, and leads up to chapter ii., which deals 

 with the habits and economy of the non-marine forms. 

 Knemics of the mollusca, means of defence, parasitic 

 mollusca, commensalism, and variation occupy the next 

 chapter. Field malarologists especially will appreciate 

 the bionomical facts and fancies here carefully gathered 

 together from innumerable minor sources, and presented 

 in available form ; indeed, were it not from lack of space, 

 wc would gladly quote largely out of this, the most 

 interesting portion of ihe work from a popular point of 

 view. In the succeeding four chapters (v.-\iii.), the 

 anatomy, or rather the comparative anatomy, and embiyo- 

 logy of the several classes are dealt with. The shell and 

 the designation of its parts come next. Distribution (in 

 space) forms the theme of the three subseijuent chapters, 

 and here the non-marine have preference by two to one 

 over the marine inollusca. Three maps accompany and 

 "illustrate" this section, by obviating the necessity of 

 referring to an atlas. Finally, there is the systematic 

 portion, in which a brief description is given of the 

 principal 1 h.iracters of each family with its distribution in 

 time, and a list of the more important genera composing it. 



NO. 1337. VOL. 52] 



In great part, therefore, the present work reverses the 

 method .idopted in most modern text-books, wherein it 

 is customary to describe the animals first and discuss 

 their habits afterwards ; the writer has, in fact, followed 

 the arrangement adopted in the preliminary chapters 

 of Woodward's " Manual," rather than that in Fischer's. 

 This system of inversion also obtains in the anatomical 

 portion; reproduction, usually reserved for the last, being 

 put first .ipparently, with some idea of starling at the 

 beginning of the molluscan career. The principle may 

 undoubtedly possess advantages, but it also has its draw- 

 backs. For example, the nomenclature of the parts, ( r 

 topography, of the shell is not given till the close of chapter 

 ix., whilst many of the terms there first defined have 

 previously been freely employed, and that although the 

 student is theoretically not expected to 1)C acquainted 

 with anything beforehand. 



This is a detail which the editors should have attended 

 to, for wherein their utility if not to assist by bringing a 

 fresh and impartial eye to bear on the work they super- 

 vise, since however able a writer may l)e, he is naturally 

 apt when engrossed with his task to overlook such 

 minuti;e. -So, too, they should have noted that the 

 "classes" have in the opening 

 pages, by a slip of the pen, been 

 c ailed "orders." They might also, 

 though it is not fair to charge it to 

 their account, have observed that 

 wlnist at p. 14 /^/rissi-nsi'ii and 

 Myfi/o/'sis ,ire spoken of as 

 " scarcely modified .1/v//7t\" these 

 two genera are in the systematic 

 part correctly referred to a totally 

 (litVerent order from Myti/its. The 

 author himself, however, must l)e 

 held responsible for having over- 

 looked Dr. Carpenters retraction 

 of his theory of shell formation in 

 the later editions of "The Micro- 

 scope," and for such other over- 

 sights as referring the well-known 

 and beaiuiful Clioanopoiiui /lys/n.w 

 fniMi Culia.to the genus Cylimlrcllii^ 

 or describing .s//vi////'//.t as " frugi- 

 vorous." 



.Mthough on so vexed a ques- 

 tion as classification the greatest 

 \ ^» latitude seems allowable, yet certain 



V'Sli*-—/^ points in the one here adopted call 



N^^>^~p;jy for remark. l'"or instance, the 



.Ampliineura are retained as an 

 order of (iastropoda (Mr. Cooke 

 prefers the older and, we think, less correct spelling 

 of (Gasteropoda) in ronlradislinclion to the opinion of 

 recent authorities such as I'elseneer, Simroth, ivc. More- 

 over, by-lhe-by, why is I'ilsbry's classification of the Chitons 

 passed over for an oUler and less complete one .^ What to 

 do with the I'leropoda. Mr. Cooke was apparently in doubl 

 when he began his book i pp. 6, 71, biU in the systematic 

 pari at the close, their affinities with the Teclibranchiale 

 Opislhobrant lis is duly pointed out. .\t the same lime, 

 though their two main tlivisions, 1 Ik cosomala and 

 Ciymnosom.it.i, are most closely allied to the liulloidea ami 

 the .\plysioidea respectively, the Fleropoda are here for 

 convenience sake retained as a group by themselves ol 

 equal rank with the Tectibranchiata as a whole. This, 

 if not exactly logical, is coni|)rehensible, but not so the 

 separation of these two sections by llu- inli ipositiim nl 

 the .Ascoglossa and Nudibranchi.ita. 



About the lleleropoda, on the other hand, our aiulmr 

 has no scruples, and though they retained their inde- 

 pendent e to a later date than the l'leroi]oda, they arc 

 referred without commenl, albeit correctly, to the I'roso 

 br.inc hiata, and even, following l.ang, to the TaMiioglossa. 



