(12) 



EXPLANATION OF THE PLATES. 



Fig. 4. Eve, with a larger part of its surroundings, o 

 eye; e c e marginal circular tube; c c outer tubes; 

 i I marginal folds inclosing the ocular appai-atus; f/f 

 radiating chymiferous tubes \ d d d tentacles. 



To understand correctly the sections represented in figs. 

 5, C, r, 8, and 9, the direction in which they are cut 

 should be first ascertained by a comparison with figs. 

 I, n. VI. and VII. .Suction 5 runs from the centre, be- 

 tween two ovarian pouches, to the margin of the 

 disk. If it were prolonged across the whole ani- 

 mal, it would divide fig. 1 of I'l. VI. and VII. into 

 halves ; and the part represented corresponds to 

 the right siile of the upper half, the tube running 

 between the bisected ai'm b and the ovary r, along 

 the lower surtace of the disk, Ijeing one of the ehy- 

 miferous tubes which arise from the main cavity of 

 the body. Figs. 7, S, and '.) also jiass through the 

 centre of the disk, but extend through the centres of 

 two opposite ovarian pouches, that is, they run at 

 an angle of 4.j'^ with the section fig. 5, or oblicjuely 

 across fig. 1 of Pis. VI. and VII. In fig. 7, the cen- 

 tral pyramid of the disk is removed to show more 

 plain!)' the mode of communication of the ovarian 

 pouch (( p, witli tlie central cavity of the liod}- s ; 

 and, to bring these relations more plainly into view, 

 the left ovarian pouch is also rcniuvcd, and in the 

 right ovarian pouch the veil which separates the 

 pouch from the blind sac lielow is removed with the 

 o\aries themselves, while in figs. S and 9 they are 

 left in place. Fig. 9 corresponds to fig. S, except 

 that fig. 8 passes through the centre of the poucli 

 and shows the cavity from one side and fig. 9 fi-om 

 the opjiosite side, the section passing somewhat ob- 

 liipiely through the pouch. Fig. G is a transverse 

 section across an ovarian pouch from side to side of 

 the pouch, and not, like all the others, radiating from 

 the centre to the periphery. 



Fig. .5. Section across the disk, including the centre and 

 one side. o pyramlil of the centre; /) veil forming 

 the lower floor of the sexual pouch ; y channel lead- 

 ing from the central cavity into the sexual pouch ; 

 r sexual organ; n sexual pouch; .v central cavitv; 

 a a oral lobe ; h its stem cut through ; c c its mar- 

 ginal folds; m m upper fioor or gelatinous mass of 

 the disk. 



Fig. G. Sexual pouch, seen from [\w side opposite its com- 

 munication with the central cavitv. il il lower floor 

 of the disk ; p arch of tlie veil /<', wliich separates 

 the sexual cavity u, in which the sexual organs r r 

 are inclosed, from the Ijlinil sac /] whii'li is below and 



communicates through the hole _/" with the surrounding 

 medium. 



Fig. 7. Another section through the centre of the disk, 

 across two opposite ovarian pouches, leaving one, in 

 the centre of the figure, entire in the distance, s cen- 

 tral cavity; a a oral appendages or arms; I b stems 

 of the oral appendages cut through ; c c marginal folds 

 of the arms ; d and e the thickened pillars in the lower 

 floor surrounding the hole /, below the sexual cavity ; 

 r )• sexual organs; j> veil forming the lower floor of 

 the sexual pouches ; n sexual cavity ; m m upper floor. 



Fig. 8. Another section passing through a sexual pouch. 

 pyramid of the centre of the disk ; s central cavity 

 of the body ; a oral appendage or arm, cut through 

 at b\ c c its marginal fringes; (/ and e lower fioor 

 thickened and inclosing the blind sac /; q channel 

 leading from the main cavity into the sexual pouch 

 n ; )• sc-xual organ ; y/' veil separating the sexual 

 pouch from the lilind sac below ; m m upper floor. 



Fig. 9. Another .■section, passing somewhat obliijucly through 

 a sexual pouch. a arm, cut through at b ; d and c 

 thickened lower ficior, surrounding the blind sac _/"; 

 pyramiil of the centi-e of the disk ; ,< main ca\ity ; 

 tl channel leading into the ovarian pouch ; p veil sepa- 

 rating the ovarian jiouch from the blind sac below ; 

 ])^ section of the veil; r r sexual organ; n n sexual 

 pouch ; m m upper lloiir of the disk. 



PLATE X. 

 ScYPiiosT05i-\ OF Cy.\xi;.v .vkctica and Aurelia 



FL.\V11>UL.\. 



[Figs. 18, 22, .31, 32, and 30, Aurolia ffavidula, were dr.iwn by 

 A. Sonrel; the otliers, Cyanca arctica, by II. J. C'larli.] 



Figs. 1 and 2. Eggs from the ovary of Cyanca arctica, 

 Sept. -28, 18.^)7, magnified 500 diameters. — r vitelline 

 sac ; y if yolk ; p Furkinjean vesicle ; lo Wagnerian 

 vesicle. 



In all the remaining figures, 3 to 38, the fiiUowing letters 

 refer to the same parts. a the outer wall of the body ; 

 rt' the outer wall of the tentacle ; b the inner wall of the 

 body; c the mouth or proboscis; c" the basal or po.«- 

 tcrior enil ; (/ the digestive cavity ; c <' the tentacles ; 

 /"' the base of the horn-like sheath or tube. 



Fig. 3. A gloliular embryo, just escaped fi-i>m the ponclies. 

 Magnificil 5oo diametcr,s. 



Fig. 4. Profile view of an ovate embryo just from the 

 pouches. joo diameters. 



