272 BULLETIN OF THE 



EXPLANATION OF THE PLATES. 



br. Bridge connecting two segmentation spheres. 



cav. Cavity. 



cl. pi. Cleavage plane. 



1 d. pi. First cleavage plane. 



2 cl. pi. Second cleavage plane. 



3 cl. pi. Third cleavage plane. 

 c.p. I. Cavity of primitive larva. 



dm. Thickening of the superficial layer. 



eh. Epiblast. 



et. Undivided portion of ovum. 



fil. Filament. 



goph. Gonojihore. 



gt. Oil globule. 



Kb. Hypoblast. 



hyph. Hydrophyllium. 



9?i. Membrane. 



mb. Mesoblast. 



n. Nucleus. 



nl. Nucleolus. 



om. Ovum. 



pg. Polar globule ? 



pig. Pigment spot. 



pr. Primitive furrow. 



pr. hyph. Primitive hydrophyllium. 



■^' •^' \ Pneumatocyst. 

 py. cy. \ 



pn. ph. Pneumatophore. 



pyt. Polypite. 



r. pol. Posy pole, when not indicated, upper pole of figure. 



r. tb. Eadial tube. 



se. Secondary furrow. 



ser. hyph. Serrated hydrophyllium. 



1 scr. hyph. First serrated hydrophyllium. 



2 scr. hyph. Second serrated hydrophyllium. 

 tb. Tube. 



ubr. Umbrella. 



vel. Velum. 



vt. Vitellus. 



