148 



THE VOYAGE OF H.M.S. CHALLENGER. 



K. Cathammata. 



Lines of Fusion. 



Verlothungen. 



A- Concrescentice, Fused parts, Concrescenz-Platten, 



Partes concretes. Plates. Verwachsungs-Stellen. 



Places at which the two walls of the peripheric gastrovascular system (uinbral or 

 dorsal wall and subumbral or ventral wall) are fused or grown together ; they sometimes 

 form round knobs (nodi), sometimes line-like selvages (septa), sometimes fiat plates 

 (laminse). Each cathamma, or junction, always consists originally of two epithelial 

 plates of the endoderm, which are, however, often fused into a single layer of cells. 



Id Lobomm cathammata. 



kn Nodi cathammales. 



ht Tabulae cathammales. 



ks Limites cathammales. 



Fused clasps of the margiual lobes. 

 Fused nodes. 

 Fused plates. 

 Fused ridges. 



Lappen -Spangen. 

 Verwachsungs-Knoten. 

 Verwachsungs-Tafeln. 

 Verwachsunss-Leisten. 



L. Lobi. 



Lobes. 



Lappen. 



1 Lobi marginales umbrella;. Marginal lobes of the umbrella. Lappen des Schirmrandes. 



Leaf-shaped processes of the umbrella margin, separated by clefts in the margin, and 

 usually containing peripheric processes of the gastrovascular system. The true marginal 

 lobes (homologous to tentacles) are only found in the section Ascraspeda ; whilst the 

 false marginal lobes, which sometimes appear in the Craspedota (in the Narcomedusse) 

 are formed in quite a different way (gelatinous lobes, arising from the development of the 

 peronia). 



By far the larger part of the muscles of the Medusas belong to the subumbrella, and are 

 produced by its ventral ectodermal epithelium ; the dorsal muscles which are formed from the 

 ectodermal epithelium of the exumbrella, and the gastral muscles which are formed from 

 the endodermal epithelium of the subunibral gastrovascular wall are much less important. 



