SERTULARIA. 191 



the origin. On divulsion of a specimen 27 inches high, from a shell, where- 

 on it had been founded, a scale from the shell, under a line in diameter, 

 sustaining the root, was separated. Here the stalk scarcely exceeded the 

 size of a horse's hair, and consisted of a single tube. Four branches, in 

 alternate pairs, issue from around the stem, nearly in a horizontal direc- 

 tion where lowest ; and they subdivide dichotomously, or always by cleav- 

 ing in two. — PI. XXXVIII. fig. 1. These branches are short, contrasted 

 with the length, for the tallest specimens might be contained in a vessel 

 of about two inches diameter, whence the branch must be little above one. 

 The general aspect will be seen from the Plate, XXXVII. Deep annula- 

 tions indent the stem and branches at irregular intervals, comprehending 

 from two to ten cells between them. These are more conspicuous in nas- 

 cent specimens or in decaying adults. Two rows of conical cells, slightly 

 curved like a horn, clothe the sides of the stem, branches, and their sub- 

 ordinate parts ; but under considerable discrepancies in form and position. 

 Those on the stem of younger specimens are sufficiently conspicuous, but 

 the profusion of branches on the older obscures them. In these, the 

 latter, they are more in front, in the former, more on the sides ; their true 

 arrangement alternate. It is to be remarked that the precise relation of 

 the parts is affected by the increment of zoophytes ; which creates some 

 embarrassment in an observer comparing his subject with the observations 

 of others. A notch appears in the orifice of many of the cells of this 

 species, which is so deep in some, that the higher parts approximate a 

 spinous formation. — PI. XXXVIII. figs. 2, 3. The annulations of the 

 stem, which are also a prominent feature in younger specimens, may readily 

 escape notice in adults, both from the presence of extraneous matter, or 

 on selecting too short a portion for inspection. Obliteration of the pith 

 contributes to their exposure. 



Considering the ample dimensions of this Sertularia, its hydra, with 

 20 or 22 muricate tentacula, is very minute. — Fig. 4. To the naked eye 

 it is a mere speck, pure white, or of greenish hue. The contrast between 

 these pale animals and the yellow or yellowish-brown of the rest of the 

 product is great. 



The Sertularia argenfea is a zoophyte to be characterized as flexible 



