SOS 



i:ciuxoim:rma 



r' ^n ni h 



cloac;'.. ^Taiiv ;:ooiotrist> rcj;aril thorn as ilcfcnsi\-c structures lu-causc of 

 their siiek\- nature auJ Neeause they eaa be cast out thi'ouL^h the anus. 



The iTsophauus is u^ualh- surrouiiileil hv a riiiL; of li\e raiHal aiul li\e uuer- 

 raihal plaies which ser\e a> peiius of aliachmeiu fer ihe lunL;iunhaal nuiscles. 

 |usi behind il He ihe riui; canal, ring iier\e, anb ihe rin^j; ^A ilie bloeb s\sn ni, 



each uiNinL; iiff li\e rabial hraiiches which run 

 v> J iiisibe ilie nui>cular sac oi ilu' bculw Ircni 



tlie beL;innini; e>f ilie rabial canals ^ran-ly, as in 

 Svi:<i ,''!•!. frnni ihe rini; canall lubes i-xuaul lUit- 

 warb to form bie cMrenu-h" sen>ib\e reli'acble 

 tcniacles w hicli surreunb the nuauh. anb \\ hich 

 either brancli \ I 'enbrechirolaO er bear lriHi.(l 

 shielb-shaj'cb exli-cnhbes i, Aspiboclnroia'h \ 

 single Tolian wsicle i■^ usaallv preseiu, anb 

 the occa>ionallv lirancheb suaic canal connecls 

 (exce|il in the Ibasipebal wibi ihe Cieloni. 

 liloob-xessels gibng from ihe \a-.cular ring 

 Fic. _;oQ. — Transverse sccuon f^,,.,,, (.j^.], aiiaslomoses on the alinienlar\- canal, 

 of We/c//,«/-,a/,,/.,,/.,,-,Mafierlaul- ^-j,,,^. .j ,„ .|^, ^,^„^.,,| ^,„. ,, p,,ir of' unilcb 

 Aviir). (/, digcsnvo traeu t;/'. dorsal - , , ' " .,,, ■ ■ ,■ 



,, , V 11.1 gonads) occurs. 1 his consisis ol nnnierous 



hlooit-vossel; c, gouail duet; ".',,,., . ,■ ,, ,, 



skin; /»,, longiludinal muscle^; Ubniles which o].en inlerrabially, ii.sually near 

 /■:e. left branchial live; iii. meson- bie niouih. 



tcries; r', r-'. aiiihulacral coin]ile\ The regenerali\e powers of ihese animals 



of hiviuin unnlnilacral wssel) and are of inleresl. In iinfa\orable conbibons 

 Jier\e; r'-r\ same of triviuin; )-:e, du-y voib the whole \ascera anb \el nia\ li\e 

 right branchial tree. .^„^^ reprobuce the lost parts, "in cerlain 



species are founb a few parasites. C^ne or 

 two harbor a small fish (FirrnsUi) in iheir cloaca and branchial trees, while 

 parasitic snails [Eiitocoiuini, l'jitoi;>lii.v, J-'nlcit'Xti.-ns) li\e in se\eral species and 

 a mussel, Eiilovdlva inirdhilis, in another. 



Order I. Actinopoda. 



Radial canals present, sending branches to the tcniacles ami anbnilacra 

 ■when present, nixabeb into Tcbata, wilh ;unbulacr.i, anb -\pob,i without. 

 The rEDA'iW inclube the lloi.ormi;iicr; with pcli.iie teni;icles, ^ Aspibo- 

 chirol;ej. HoU'thur'uf'' in warmer waters, one species forming the lrep;ing of 

 Chinese m;*rkets. 0{ the forms with branched tenuicles i l>endroehirol;e"l are 

 the CrcxTAi,\Rini,i':, Ciifimiariii," I's.'liis,'-' I'h vi-nc/- The deep sea Ifi \sii'on\ 

 ha\"e slalocysts and peculi;ir dorsal ambiihicral processes, 'idle .\POn.\ ;ire 

 represented by Cdiuliiui'' and M iilpkulid/'- 



Order II. Paractinopoda. 



Xo radial canals nor anbnihicra. Tenlacnlar can;ils arising from ring 

 canal. .]t yri,:lnulin.^/-- Sviui /'l,i -- with slalocysts, ('//i,'e/;-,ic/,7/,v.- ' In PiidrX 

 tliiirid the anterior end is expanded U) a disc with tent;icul;ir processes, useb in 

 swimming, like the bell of ;i medusa. 



Summary of Important Facts. 

 I. The ECIilNODKRATA sl\;uo the rabi;ilc structure wilh the 

 tbvlenferata, hut differ from theiu (a) in the uunierical b;isis of the 

 symmetry (live); {h) in that, as enbiryology shows, they have bescenaed 

 from liilateral forms. 



