44 R. T. Günther 



The withdraAval of tbe cuidophors is not only efifected by the dimi- 

 nutiou in leiigth of the stalk and its consequent thickening, but also 

 by the adoption of a spirai disposition (fig. 17 e), like the stem of 

 a retracted Vorticella. 



The Biniilar enidophors in Geininaria and Ptei'oneina seem to be 

 more pleutifully supplied with nematoeysts, and if drawings of them 

 are to be trusted, are rather more pointed in shape. In Gemmaria 

 moreover the enidophors are furnished with long vibratile cilia 

 (Allman). 



Ectoderm of Subumbrella and Velum. 



The ectoderm of the subumbrella is almost entirely eomposed 

 of long fnsiform miisde cells with elongate nuclei (hg. 11). The 

 preparation shown in tig. 12 was made from au animai which 

 had bcen kept alive in seawater tiuged with soluble Carmine. The 

 niuscle tibres remained unstained, but their nuclei became light pink 

 and there appeared a number of round vacuoles of all sizes tilled 

 with Carmine solution. The largest were larger than the nuclei, the 

 smallest were extremely small. 



The velum is also strongly muscular. It is eomposed of two 

 layers of flattened contractile cells of a peculiar nature. Claus 

 originally described such cells as part of the "Öchirmmuskulatur", 

 but in all specimens which feil into my hands, the cells of Claus 

 occurred only in the velum, the musculature of the subumbrella 

 being invariably eomposed of elongated cells like those described 

 above. The illustration given by Claus (tig. 13) of a single cell 

 seems to me to be a correct representation of a velar muscle cell. 

 In shape, widest in the middle and tapering towards the ends; 

 nueleus oval, with one or two nucleoli, in the broadest part of the 

 cell; cytoplasm for the most part hnely granular, but traversed with 

 transversely striatcd fibrillae (myonemata) which occasionally brauch, 

 but 011 the whole run parallel to the major axis of the cell. 



Mesogloea. 



The mesogloea is structureless and devoid of immigrant cells. 



The mesogloea is fairly well developed in all regions of the 



body. A noteworthy feature is that it thins out and is absent in 



