I' II ics J I w A T v.n (■ K.\ V V I s 1 1 V.H () I • A 1 1 s'l l^^ M A . ] 4 7 



of the I'ivcH's. Tlie sj)ecies, in tliis case, woulil li(> always 

 recruitiid from the small inland forms. Wliebher this suggestion 

 holds gooil or not, the problem of wliy small individuals have not 

 hitlierto been found in the streams whore the large 'J'a.smania?) 

 and Muri-ay River- fJrayflshes oeciu' i'i;f(uires soti ling one way or 

 the othei'. 



Since this q\iestion at present, remains open and I have found 

 it impossible to discover mor|)hological j)()intsf)f any value between 

 the larg(! and small forms of these species, I Irave not ti'eated 

 them as distinct species. 'I'his leads to the irrclusion uirder one 

 specific n.'irrre of tiie very widely distributed form A . serraUis, 

 which occurs in the Mui'ray Kiver and its tributaries, in the 

 Victorian rivers such as the Yarra, IMenty, and Bunyi]) Jiivers, 

 again in tlie Paramatta, River at Sydney and in the Blue IVloun- 

 tains. This is a, ti-uly imnrense range for a s[)ecies sncli as this 

 to occupy, which, so far as we know, never for'sakes the water- for- 

 any length of tirrre and has been presumal)ly slowly distr-ibuted 

 l)y the slow alter-ation and communication of diflerent i-iver- 

 systems. Marry of these wiik^ly sejiarated communities of Cray- 

 fishes cannot have irrterbi-ed for- centuries, almost for- geological 

 periods, and yet they liave retaiired the common s[)ecific cliar-actei-s 

 with r-emai-kal>le constancy. It is true that an immense r-arrge of 

 var-iatiorr in size and in tire degree to whicli the .spines ar-e 

 developed is met with irr these local gr-oups, but these characters 

 show gr-ad nations, and the development of the spines is so variable, 

 being often a.symmetrical on the two sides of one specimen, that 

 they do not offer constant specific cliaracters for .separating the 

 various groups. It a})pears to me certain that it is impossible to 

 separ-ate the large Paramatta Crayfish fi'om the large Muiray 

 River for-m, and yet these two large r-iver-s belong to two different 

 systems, their near-est point of appr-onch 1)eing in the Blue Moun- 

 tains on differ-ent sides of tlie watei'shed. With the material at 

 my disposal .1 anr irrrable to split up these various local s]H'cimens 

 of A. serrattin into a. numl)er' of subspecies, a.lt.liough I do not 

 wish to }»i-ejudice the work of some futur-e irrve.stigator- who, with 

 nior-e matei-ial at corrrmand, may feel liimself corrr})etent to do s-o. 



I i. 7'he Rdatinnships of the Anstralkm Crai/Jishes 

 and their O'eo[/raphical JJiHtrihjition. 



The Crayfi.shes of Australia, Tasmairia, and New Cuinea. belong, 

 in common with tho.se of New Zealand, South America, and Mada- 

 gascar, to tlie family Parastacidje, whiclr differs from the Crayfish 

 family of the Nor-ther-n IJenris)>her-e, tlie Astacida% in a nrnnlrer of 

 important cliaracter-s Avhich were first pointed out clearly l)y 

 Huxley. The diagnostic featirres of the Par'astacida? given Jiy 

 Iluxley (P. Z. S. 1878, p. 775) are as follows : - 



" The j)0(l()l)r-anclrite are devoid of more than a rudiment of a 

 lamina, though the stem may l)e alate. 'I'he ])odol)ratrchia of tlie 

 fir-st ma\illi[)ede has the for-m of an (•pip(,dite; but in almost 



10* 



