No. 484] .4 TTA CHED YO I Xd OF ( 'RA YFISH 



259 



lobes and setvc aid respiration in niakino; tlie inlet water more 

 free from dirt. 



The chela% figure 10, are long and strong but as yet not sj)ecial- 

 ized as cutting organs. The tips of the claws are i-ecm-ved as 

 Huxley first found them to be in the P'nglish Astacus so that once 

 shut upon a penetrable mass they could scarcely be loosened by 

 the larva, figure 17. By means of these lockinu" lips tli(> young 

 become fastened to the egg stalks and lo ilic liardciicd secretion 

 on the mother's pleopod seta^ so that th(y |)rol»;il)ly remain fixed 

 in one s{)ot all the time they live in the first stage. Tlie simple, 

 acicular seta" seen along the edge of the chiw, figure 17, may pos- 

 sibly aid in tactual reflexes to enable the hu-\ a to shut its claw on 

 suitable substances. 



The next two pairs of legs are very like the cheiic, l)ut more 

 slender, short and weak. 



The fourth leg, figure IS, with no claw, has its arthrobranchs 



The fifth leg has no nilU al all aLoeiate,! ^\ith if! tlie pU-uro- 

 brancii of Astaeus l>ein- absent n..t oi,K in ilie a^luh ("an. hams 



deternii.ied by Faxon, in ('. rustirus. The hrancliial fornuihi'is 

 thus the sanu> in the larva' as in the adults. 



On the abdomen the appendages have the incoinpleteness of all 

 crayfish larva'. The first pair are not begim and the sixth {)air 

 are forming under the exoskeleton within the base of the lelson. 

 The other four pairs are vety small and apj)arently (piite useless 



abdomen and with the endopodite more aincriov and the exopodite 



the larger and both endopodite and exopodite ai-e \eiy simple and 



The telson, figure 'J. is a simple, (-lonuaicd, llai plate showing 

 within its elear'sul.siai,.-e ra liaiin- lines ni,lin- at (he nuirginal 



spines ;„m1 aU,, thr oudine^ of tlu' Ion- exopodiles of the sixth 



pleopods Ixin- alon- on ea( li ^de <.f tlie ,eetum and anus. On 

 the veiural side, figure 1 . ihe l.as,- ,.f the telson is <|niie protui)erant 

 over the part of tlu> enclosed [)h-op()d that will i)e the exopodite. 



