MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. ' 99 



7. KROHN, A. " Ueber eineu neuen Ent,vickelungsmodu« der OpUiureu." Mueller's Archiv. f. Auat. „. Phye., 1857, 



8LVMAVT '.OphinrabrevispinaSay." Pt. I. 111. Cat. Mus. Comp. Zool., Harvard Coll. 1865, p. 16. 



giv^T. "Report on the ..phiurid.." Vol. V. Challeu.er Keport 

 10 McBK .K E W " The Uevelopment of Asterina j^ibbosa." Q. .1. Mic i^c vol. 38. 

 n ;i.;vK.C"w "Ueber die Bew4u,.,en der Seesterno." Mitth. . d Zool. Stat z. Neapel. de... 1886. 



Zeitschr. f. Naturwiss. XXII. 1888. 



EXPLANATION OF PLATES. 

 The r,p,res illustrating this paper were drawn to tUe sau.c scale of n,a,.ufication. 330 diameters, and were 

 reduced o,.-l.all^in ™I-' J^;;;- ^^^^ ..constructed iron, series of transverse and sagittal secticn^s. 



Kll 'ci's 'the paH of the figure which is nearest the top of the plate is either auter.or or else ventral .n the 

 larva. 



ABBREVIATIONS USED. 



Left anterior enterocrole. 



" Eight anterior enterocujle. 



^^^ !...'...".'.-."---..'-- Apical plate. 



"'^". Axial Sinus. 



ax sin _,, . 



Blastopore. 



JV'o'o" "Vi Ciliated bands. 



cbl,2,3,and4 



' Circular groove. 



"^ Circular mesentery. 



'^^ Cellular plug. 



' Dors.al pore. 



* Epigastric enterocwle. 



End tentacle. 



® ~ Canal connecting posterior en- 



teiocii'le and hydrocn-le. 



Hypogastric enteroco'le. 



1^ "/n'o'r.'-i'y'iLk Interiadial pouches of the hvpo- 



hip 1-2, 2-3, 3-4, 4-0 ^. \ i„ 



'^ ' gastric onteroc<i'le. 



HydrocH'lc. 



. Inner pcrihieiual sinus. 



IP^""; Intenadial pouch of axial sinus. 



ipaxSl ^ , 



. Larval organ. 



Mouth. 



Mesenchyme. 



mes .. . , 



First pair tentacle nerves. 



ul ^, ' . 



Nerve ring. 



nr 



n.sophagus. 



, Oral disk. 



od ., , . 



. . Outer perihicmal ring. 



opr 



Pore canal. 



^ Posterior enteroccoles. 



Poliaii vesicle. 



pv - 



, Radial nerves. 



rad n „ , . , 



Radial grooves. 



" Radiiil perih^mal space. 



Z aV.'.:v;.;v.'.v;::'.".".;".v.v.;'."v.;v;.:.:;v.;;' v;. ■ sinus " a^^. 



siub Sinus "b» 



„. Stone canal. 



8t , . 



Subneural sinns. 



Stomach. 



.^ Fir.st pair foot tentacles. 



., Bnccal tentacles. 



.. Water vascular ring, 

 wvr , . 



I II III IV V -^^"^ rudinionts. 



,'oo,'- ' Radial water canals. 



1,2,3,4,0 



