4 THE VOYAGE OF H.M.S. CHALLENGER. 



thickish, irregularly rounded or flattened stems of the consistency of soft sea-wee'd, and 

 having a slight lustre like the semitransparent tubes of many Annehds. The stems 

 have a diameter varying from four or five millimetres to double or treble that breadth in 

 the flattened expansions ; but the general size of many of the branches is nearly uniform. 

 They cover a considerable area with their network, the extreme length in one example 

 being about 9 inches, and the breadth 5 or 6 inches. The main trunks appear to 

 have sprung from submarine objects, such as stones or sponges, but instead of standing 

 erect as in a soft Gorgonian, to which the inosculations of the branches give it some 

 resemblance, they seem to have been more or less horizontal, since pillars of the 



W.O M. 



Fig. I.— Fingment of Polyzo&num o{ Cephalodisciis dodecalophns, M'Intosh. 



ccencecium occasionally pass, like aerial roots, from the underside to the plane of attach- 

 ment. Various foreign bodies, such as tubes of Serpulse and portions of sponge, are, 

 moreover, occasionally enveloped by the ccencecium, the originally soft secretion having 

 insinuated itself into all the irregularities of their surfaces, and extended around and 

 beyond them. The surface of the branches is everywhere studded with elevations and 

 ridges, which terminate in long spines of the same tissue — simple, bifid, trifid or multifid — 

 and here and there bending downward to join the main stem, so as to form loops and 

 arches, or inosculating with adjacent spines or fimbriae (woodcut, fig. 1). Some of the 



