PLATE XIX. 



LAOTIRA CAMBRIA (p. 32). 



Fig. 1. Exurnbrella view of a specimen in which the tendency to fission is strongly developed. 



Fig. la. Subumbrella surface of fig. 1. 



Fig. lb. Side view of fig. 1. 



Fig. 2. A worn specimen in which fission has proceeded so far as to leave but one lobe, connecting 

 what are otherwise two individuals. 



Figs. 3, 3a. Exumbrella view of a specimen in which fission has proceeded so far that there is appar- 

 ently but a single lobe uniting the two parts. This is still better shown by the subum- 

 brella surface, fig. 3a. 



Gastroblasta raffaeli (p. 39). 



Figs. 4-8. Scheme representing the successive fission of a supposed first radial larval form. (After 



Lang.) 

 Fig. 9. A medusa in which the first stages of division are indicated. (After Lang.) 

 Fig. 10. A different stage of division and binary fission in which two stomachs are developed and 



the fission is more advanced. (After Lang.) 

 General meaning of the lettering: m, stomach in its inception; g, gonads; t, tentacles; r, 

 radial canals. 



The different ages of the gastral cavities, gonads, tentacles, and radial canals are shown by 

 figures, viz: i, the oldest tentacle; tJ, the second-oldest tentacle, etc.; m, the oldest stomach, m3, 

 the second-oldest stomach, etc. 



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