I I II) MERISTIC VARIATION. [PARTI. 



Passing now to the question of the distinctness of A. niilhiniiirnii, it seems clear 



tlnit. ke said, it should never have been considered a distinct species. The 



the Unless tail, which is now seen to be one of degree, does not differ - 



lorily, and, as Schmankewitsch found, it is to be seen swimming 



\utli tin i individuals. It has never been shewn that there is a male A. mil- 



\utb distinctive sexual characters, and among the Branchiopoda the 



-cxual characters of the second antenna in the male are most strikingly 



ictiv* "i tin- several forms. While being in no sense desirous of disparaging 



uankewitsch's very interesting observation, I think it is misleading 



ihe the change effected as a transformation of one species into another. 



bach himself expressly said that he did not so consider it, and it is 



tlnit such a description has been applied to this case. 



t inn nf th' division of the 8th post-abdominal segment of Artemia, 



ii mi dilution of the water, directly concerns the subject of Meristic 



:. A- to tin- flirts, there is no doubt that the tail of Branch ipu.f appears to 



in. 'iii- i.esidt.-s the two which bear the external generative 



in all. niiif, \vlnli- in the commonest forms of A. mlina there are only 



nt-; and that the difference lies in the fact that in the long 



t'li:. . [. galina there is generally no appearance of division. But as 



' -h<\\n. tli- la-t apparent division in Branchipits is of a different 



I'l.. m that of the other alidmninal - ' . This is indeed easily seen 



in / ah . I:. ././. is//.--. &0., MI wliich tliu ap]>. arance of tin la-t 



.on i-, \. :roin that of the other .li\ isious. It appears, in fact, to be 



I. annulatioii thai -illation. In longitudinal sections file distinction 



-u. -li a di\i-i- iin^' to Schmankewit-eh. appears in the third 



. !i ..: .1. .-.iliiiii hied in diluted salt water. 



Ann. ii/ m\ c of division in the last segment or<-urs 



in a <-. i. nuniliei, and tln-.-e are not hv any means from the most dilute 



v.atT.- iilon. . ih. in lieiiiL' from wai real e..nrentratinn. For instance, 



.men- in XXIX. LI, XXXVII. XXXIX and XIV, all have no trace of sneh 



di\i ' ': tin- oilier hand, it was found in . i . cimens t'n-m XX\"I (Sp. G. 



Tl 7'.'. al.d X I.I I i !>].. ( .. I'll.".), while (it he! s I'loln tin -e loca 1 i t i. - did Hot shew it. 



to adull t. mal. j. I do not tliml.. there! that the 



ion of this appearance of division to the salinity of the water is a constant one. 

 Lastly, It tin- relation of Art.min t.. Branc/iipus, Schmankewitsch has 



in:iinta:in d that the di\isi,,n of thi- la-t al.doininal Moment i- tin- only struetuial 



ill\ ditTei. ntiatinj.' llnnn-tiiinif. Cl.au- (Lc.) pointed out that there are 



many otin-r point- ol ditT.ieii.-e. and that the suppo.-ed di\i-ion is not a struetuial 



rlmiaet-i <.fj.-i.at nioiin-iit. Hut al.ov. all tit. -.-.-, it -hoiil.l l.<- ivm. mhei ed that by 



the -.ii. il ci the male-, liniiti-lii/iii.-, i- absolutely -eparated from .1 r1,ini<i. 



I' i l-ii ha- any t-tiu<-ture at all i . -em). M at leaf-like second anteiinsB 



"ft: I. iirnriU* \ ei riil. S.-hmaiikev. it-ch i . mal ks | '/. . (. ir . /,.. 



l"T7. I ; ' iiK-lii/in.- (e.g. /'. ferox) \\itliout the 



ap|" ny.'ntx th. i ant. nn;e ,,f I:. . ./,,,/, mi;* - : . A'r., and that the 



imi ttmia bear on the second antenna a knob, which is possibly the repre- 



'.//(i/s, hut ne\. ithele-- th, re i- no resemblance 



^h.-' : ol /'. ferOX oi of any oth. r I :r,i /I'-lnjn/^ and tho-e ol 



ni. i, and th" iv i> m, reu-.n to MII -\iial eliara<-ter.- are mo<liiied 



. "iii.-.-iiti-:iii..n of the water. Chi tatement that tin descendant^ 



' 'in he ma, i une the charai BrancAtpiw Schaffer, depends 



. nt 11 el \ on the acceptance ol s.-hmanke\\it-eir- priterion <.t thai genus, which is set 



up m prn<-ti 1 -al di-ie,'.iid ..f th. far more di-!inrti\e -exual d It is, besides, 



t.it.d, only an in. -ulai and ]..--ildy mi.-leadin;' relation \\hirli 

 ' ' Etnd the salinity <! th, \\atn 



1 J " : - -" l( Wien, 1886, p. 18; also /./-/, .ihh.in.ll. ar.ttiii'K'n, 1873 

 . . I i Lft 



Ann 11. -an foim I am ind.hted t,. l>r A. M. Norman 

 who i. .. i\, d tin m fioni Profl 101 I'.ii l.ai.i. 



I cannot lea\.- tin- -nhj, . t v.ith,, -loiii-liin.-nt at the com- 



ll -' 1 ' 1 '" ' in the structure of Art.'ini,, and other 



i inhabiting uat.i- ,,f dilt, i, nt salinity and composition. It is not a little 



