224 THE VOYAGE OF H.M.S. CHALLENGER, 
P. Cavity of the sac of the zooid, occupying, in the recent condition, the 
wide upper chamber of the dactylopore. 
D’. Another dactylozooid, seen in section. The zooid, being doubled 
back into the outer part of the dactylopore where cut in section, 
its cavity appears partly as a lumen at TT’, partly as an elongate 
hollowed area, in which are seen the strong longitudinal retractor 
muscles of the zooid. 
C, C. Tortuous canals, offsets of the general ccenosarcal meshwork, which 
pass radially outwards in the substance of the pseudosepta, between 
the pores of the dactylozooids. The canals ramify as they reach 
the outer margin of the calicular system, and join by their branches 
the superficial outer network of the coenosare. 
N. Large ovoid nematophore, full of closely-packed nematocysts. One 
such nematophore is present in each imterval between the outer 
margins of the mouths of the pores of the dactylozooids. 
Fig. 3. Earliest stage in the development of the ovum in Cryptohelia pudica. 
A bud-like mass of endoderm cells is gathered together within an offset 
of a branch of the coenosarcal meshwork. 
Fig. 4. The same, in a further stage of development. 
O. Ovum, with germinal vesicle and spot. 
S. Spadix, composed of endoderm cells. 
E. Thin layer of the ectoderm, continuous with that covering the spadix, 
and investing the free surface of the ovum. 
Fig. 5. Section through a planula of Cryptohelia pudica, in a very early stage. 
E. Ectoderm. 
En. Endoderm. 
Fig. 6. Portion of a planula of Cryptohelia pudica, in a more advanced stage than the 
foregoing, viewed from the outer surface. 
KE. Ectoderm, transparent, and showing a demarcation into the poly- 
gonal areas. 
En. Endoderm cells, seen through the transparent ectoderm. 
Fig. 7. Section vertical to the surface of a planula of Cryptohelia pudica when fully 
developed and ready for exit from the broad sac. 
En. Endoderm, composed mainly of oily globules. 
KE. Ectoderm, which is extremely thick, and for the most part trans- 
parent and gelatinous in appearance. 
N, N. Nematocysts. 
A. Tracts composed of small, rounded, non-transparent ectodermal 
elements, which run from the endoderm region at intervals ver- 
