22 HYDROIDS COLLECTED BY THE " HUXLEY " FROM 



manufactures the tube and also secretes inside it thin layers of 

 perisarc, which form a kind of coarse network (Fig. 4). Then from 

 the root arise auxiliary tubes (stolons), which creep up the stem. 

 From the auxiliary tubes bud forth numerous hydranths. At first 

 the hydranths are sessile, and later on some develop a stalk; some 

 are more vigorous than others and develop a long stalk, which becomes 

 a branch, and is similar in structure to the original stem. Along the 

 branches there creep from the root more auxiliary tubes bearing 



Fig. 1. 

 Bimeria hiscayana, n. sp. x 4. 



hydranths. This process is repeated again and again, and results in 

 the formation of an arborescent colony (Text Fig. 1). 



The auxiliary tubes frequently anastomose with one another, and 

 form a dense matted mass, which gives a considerable thickness to the 

 principal branches. 



The coenosarcal tube of a hydranth, which forms a branch, apparently 

 has no direct communication with the auxiliary tubes growing over 

 the external surface of its perisarc. It is, however, in communication 

 with other hydranths by means of its own auxiliary tube, from which 

 it originally developed. The tube formed by the hydranth even when 



