Mr. A. '1'. .Ma.-tiriiiaii on the /'bw/ o/"Sagitta. 441 



one or two small colonies ot" Ohclin obtained in the bottom 

 tow-net were preserved, on account of the fact that they 

 jiresenteil a ciuioii.s ajipearance, several of the |)olyps 

 haviiif^eloni^ated processes attached to them. Prof. M'Intosh 

 recently handed these specimens over to the writer to examine 

 more closely; and an inspection soon showed that the elou- 

 <i;ated processi.-s were young Sw/itUv lirndy united to the 



¥v^. 1. 



Fiff. 2. 



contracted polyps. In figure 1 will be seen a drawing of 

 the apical group of polyps of a hydroid colony, showing no 

 less than three more or less digested Sagittm. In figure 2 is 

 seen a polyp from a similar colony, showing a Sagitta at a 

 different stage of digestion. The young SagittcB have evidently 

 been caught by the head and held by the tentacles of the 

 hydroids till death ensued. The process of digestion has 

 then proceeded, the body of the victim being slowly absorbed 

 into the digestive cavity of the polyps. We may easily 

 imagine that the young Sagittce attracted by the waving 

 tentacles, and attempting to browse on the same, are quickly 

 caught and held fast by them. Larger Sagittoi would 

 probably feed upon the hydroids with impunity. 



The digestive capacity of the Ilydrozoa seems only to be 

 limited by the size of the victim, and many instances of their 

 voracity are known. The above is paralleled by the well- 

 known cases of medusa? being found enveloping larval and 

 postlarval fish, and by a case amongst the ctcnophores of a 

 Cydipjje devouring a dead young fish, which occurred recently 

 at the St. Andrews Laboratory. 



Ann. cfc Mag. N. Hist. Ser. 6. Vol. xiii. 29 



