166 MESSKS. L. MURBACH AND C. SHEARER ON [June 16, 



make certain of this in sections. No medusa-buds were observed, 

 although they were sought for in a large number of individuals. 

 In sections, the lumen of the stomach-cavity is seen to be quad- 

 rano-ular (PI. XXII. fig. 5). In some examples the approximation 

 of the stomach-walls forces out the corners of this quadrangle,^ so 

 that they are thrown into folds something like the condition 

 described by Linko (25) in Sarsia hrachygaster. 



Colour. — Bell-margin and radial canals pale blue, proboscis 

 reddish violet or light purple. Ocelli black. 



Hahitcbt. — Victoria Harbour, Puget Sound, collected by Shearer. 

 Discussion. — This Medusa is perhaps the commonest species in 

 the waters of Puget Sound during the month of July. It was 

 seen every day in gi'eat numbers, frequently the shoals or banks in 

 places so dense as to obscure the colour of the water. The 

 Medusse allow themselves to drift passively in the tidal currents, 

 once in a while making a few vigorovis contractions of the bell, 

 then remaining quiet as before. While being carried along in 

 this manner, their tentacles are extended a considerable length 

 behind them, one individual having been noticed with its 

 tentacles extended a distance of over 9 cm., although its bell 

 measured less than one centimetre in height. "When suddenly 

 taken up from the siu-face of the sea with their tentacles in the 

 extended condition, they contract them quite slowly and with an 

 irregular jei-ky motion, the animals taking two or three minutes 

 to conti'act them to the normal length. 



The size and length of the proboscis and stomach in the 

 Oodonidse seem to be subject to great variation ; this is markedly 

 the case in this species, in which it varies from a short stump 

 several millimetres long to a condition in which the stomach 

 protrudes almost beyond the velum. One individual of G. api- 

 Gulum, kept for several days in a small jar of sea- water, had a 

 habit of resting about half a centimetre from the bottom of the 

 jar, allowing its proboscis to drop down every now and again. 

 As soon as this touched the bottom it was rapidly withdrawn into 

 the bell, and then slowly allowed to drop down again. Many 

 examples of this Medusa which have been preserved in formalin 

 show interradial contractions of the bell-surface, giving it a 

 cubical appearance ; these contractions are not present in the 

 living condition, and are caused by preservation. It may be 

 conti^ctions similar to these which Hincks (22) mentions as 

 interradial on the bell of Sarsia (Codonium) 2Jif'loheUa, and 

 which Haeckel calls " interradial furrows " in the same species. 

 The examination of a large number of individuals shows 

 considerable variation both in the size of the bell, the shape 

 of the apical canal, the general shape of the proboscis, and 

 in the length of tentacles. Apart from these variations, its 

 specific distinctive characters would seem to be: the truncate 

 shape of the bell ; the small apical process on the exumbrella ; 

 the short pointed apical canal, which is never knob-shaped ; the 



