ox THE DEVELOPMENT OP LTMULUi^ LOXGISPIXA. 81 



the second cœlomic cavit)^ linrkwnrrls the walls of the two lateral 

 memliers do not fuse togetlier at the dorsal, thoiio-li tliey do at the 

 ventral median line. 



A pair of cœlomic cavities appear in every segment, except the 

 segments of the second, third, and fom-tli appendages, in which the 

 cœlomic cavity does not appear at all. At least eleven pairs of these 

 cavities are pr<xlnced (fig. 53). The eleventli pair l)elongs to the 

 seventh ahdominal segment. 



All tlie C(Te]omic cavities develoj") towards the dorsum lietween the 

 epihlast and tlie hypohlast, and meet witli one another at the dorsal 

 median line (figs. 17, 43, 44). They des elop jnst ahove the liypohlast 

 and do not enter nor give l:)ranclies into tlie epihlastic ontgroM^ths, 

 such as the appendages and the alidominal pleurae (figs. 53-55). 



The first pair of cœlomic cavities is common to the cephalic lohe 

 and the segment of the first appendage (fig. 12). A little later this 

 common cœlomic cavity is partially divided into two hy an incomplete 

 septum lietween the cejilialic lohe and the segment of the first append- 

 age (figs. 12, 30); 1)ut as the cœl<imic cavity graduallv degenerates 

 from the jiosterior end, tlie smaller ])orti<^n helonging to the segment 

 of the first a])pendage disappears so(^n after its formation (i]o\ i;;). 

 The first Cd'lomic cavity always accompanies the stomoda3al invagina- 

 tion {i\g>^. 45, 50, 52). As the stomodaeum does not develop alwavs 

 along the external epiblast and as its disttd end takes gcadiiallv an 

 upward and tlien backward direction, and grows into the volk mass, 

 the first coelomic cavity is necessarily embedded aiming the volk (fig. 

 52). Taking the upward and then the backward direction the first 

 cœlomic cavity reaches at last tiie dorsum and tliere meets witli tlie 

 wall of the second cœlomic cavity, which has grown forward to this 

 point (fig. 17). 



Tlie second cœlomic cavity bel()ngs to the segment of the fifth 



