No. 598] SHORTER ARTICLES AND DISCUSSION 639 



The statement is occasionally met with that in barnacles at- 

 tached to a free-swimming animal the feathery feet are merely 

 thrust out, not waved about as in the rock barnacles, which must 

 create food- and respiratory-currents tor themselves. Now. it 

 was observed that when the Morion hearing the conehodermas 



for as much as four to five minutes; whereas, when the fish re- 

 mained stationary, they were alternately extended and retracted 

 about seven times every minute (at 18° C\), the extension in the 

 latter case being not so great as when their host was moving. 

 Lepas anserifera and L. pectinata were then tested as to their 

 behavior in currents, with this result: when the wood to which 

 they were attached was stationary, the rhythmic contraction of 

 the appendages was continuous, hut if a gentle stream of water 

 from a supply jet was allowed to flow past them impinging on 

 the anterior (concave) edges of the legs, they remained extended 

 for as long as ten minutes, and were spread farther apart than 

 in the absence of the current. This was not due to any merely 

 mechanical effect of the water stream, as the feet could at any 

 time be caused to contract at a touch. A water stream, striking 

 the posterior (convex) edges of the legs, led to contraction and 

 subsequent limited extrusion of these appendages. A more cor- 

 rect interpretation of the phenomenon described in floating bar- 

 nacles seems to be, therefore, that when the concave side of the 

 appendages is stimulated by a water current, the animal responds 

 by pushing out its legs further than is usual in the absence 

 of currents, while their rhythmic contraction is inhibited. It 

 should be noted that the two specimens of Conchoderma observed 

 were so oriented on the Diodon as to receive the full benefit of 

 currents derived from its fo 



. so tha 



a vigorous 

 ncans rapid, but rath( 

 ; barnacles. 



Hargitt, C. W. 1909. Further Observations on the Bel 

 colous Annelids. Jour. Exp. Zool., Vol. 7, pp. 157-1 

 Jordan, D. S. 1905. A Guide to the Study of Fishes. V< 



