ANATOMY OF LIMNOCNIDA TANGANYICA. 293 
Fie. 9.—Longitudinal section through a later stage. The glockenkern (g/.) 
has just commenced to invaginate at the tip of the bud. 
Fie. 10.—Oblique longitudinal section through a stage in which the in- 
vagination of the glockenkern is considerably advanced, and the lips of the 
aperture of the future subumbrella cavity (s. c.) have just commenced to close 
over. As the section is cut obliquely, the gastro-vascular space has just been 
missed. 
Fig. 11.—Oblique section through a Medusa bud, in which the glockenkern 
(g/.) has sunk into the body of the bud, and has become closed over by an 
overgrowth of ectoderm. Note the persistence of the future subumbrella 
cavity in the glockenkern. 
Fic. 12.—Longitudinal section through a stage at which the second 
ectodermal ingrowth has commenced. This takes the form of a solid plug of 
cells (ec¢.), which has pushed into the glockenkern and rendered it cup-shaped. 
The lumen of the glockenkern has been squeezed into a mere lamina. 
Fic. 13.—Longitudinal section through a considerably later stage. The 
forecasts of the tentacles (¢e.) have appeared, and the velum (v.) is well 
marked though as yet imperforate. The subumbrella cavity (s. c.) is large. 
Fie. 14.—A longitudinal section of a bud passing along one of the four 
radial canals (7. c.). The circular canal (c. ¢.) has also appeared in this stage; 
the velum (v.) is now perforate, and the tentacles (eight in number) are now 
free from one another at the tips, though their bases are still connected by a 
bridge of ectoderm (ect.). Note the thread-cells (czéd.) at their tips. 
Fie. 15.—Transverse section through a bud at a slightly later stage than 
the one figured in Fig. 14. The mesogloea (ms.) has begun to be deposited 
between the exumbrella ectoderm and the endoderm lamella (end. /.) Note 
the four radial canals (7. c.) The tentacles have been cut more or less 
obliquely, and are hanging through the centre of the velum (v.) 
Fic. 16.—An abnormal bud, in which the layers are reversed and which 
was found growing into the gastro-vascular cavity of the parent. ect. is the 
exterior ectoderm. The tentacles (¢e.) and velum (v.) are hanging into the 
gastric cavity (g. v.). At # x are the disconnected rims of ectoderm, which in 
a normal bud would be joined together to form the centre of the ectodermal 
lining of the oral region of the subumbrella cavity, but which have here 
become separated by the growth of the bud, which has in fact grown out 
through its own mouth. 
Figs. 8a—14a are diagrammatic representations of Figs, 8—14 respectively. 
