916 ADDENDA TO THE AUSTRALIAN IIYDROMEDUS^, 



II. 5:UB-FAMILY. TIAEIN.'E. 



36a (72). GENUS. PAND^A. Lesson. 



Tiarinse, with numerous tentacles (8-16) or more in one row. 

 Abaxial Ocelli, outside on the base of the tentacle. No peduncle 

 to the stomach. Edges of stomach connected with the radial 

 canals in the Sub-umbrella by four mesentei'ia. Four simitle 

 Gonads with smooth surface. Longitudinal lines of thread cells 

 on the Ex-umbrella. Polypcolonies unknown. 



iSOa (236). PAND^A MINIMA. Nov. Spec. 

 Plate XLIL, Figs. 10, 11, 12. 



The Medusa is semi-ovate, higher than broad. It possesses 

 eight tentacles of about the same length as the Umbrella. There 

 are eight nettlecell-lines on the Exumbrella at equal intervals, 

 which are situated in the Adradiis, but they do not appear con- 

 tinuous. They consist apparently of a series of elongate nettle- 

 warts. (Fig. 11), which taper to a narrow line at each end. The 

 line can be traced from one nettle-wart to another. All appear 

 connected by it. Subjected to slight maceration the covering 

 Exumbrella Epithel becomes loose and floats away when the 

 cover glass is tapped. (Hardening with week osmic acid and 

 macerating with week acetic acid, the time that is necessary for 

 exposure to the latter re-agent depends on the temperature and 

 varies from half an hour to twelve hours.) Then the Sub-epithelial 

 layer becomes more clearly visible and with a high power. 

 (Zeiss i\. Fig. 12.) It is easy to recognize a nerve fibre in the 

 thread which connects the nettle-warts with one another. 



The nerve fibre consists of similar fibrils and bipalar ganglia 

 cells as those which I described (1) in the homologous organ of 

 Encopella Campanularia. 



In another ])aper (2) I have pointed out that the Cnidoblasts 



(1. ) Vo7i Lendtnjdd. Eucopella Campanularia. Zeitschrift fiir Wiss. 

 Zoologie, Band XXXVIII. Seite 55S. 



(2.) Von Ltndcvfeld. Ueber Wehrthiere and Nesselzellen. Zeitschrift 

 fiir Wissenschaftliche Zoologie, Band XXXVIII. Seite 368. 



