TUBULARIA. 43 



occurrence ; the product commonly appears as a parasite on other zoo- 

 phytes, seldom on shells, rocks, or stones. 



The Tubidaria larynx rises three inches high ; it consists of a stem, 

 subdividing into several irregular ramifications, each crowned by a hydra, 

 narrowly resembling that of the Tiihularia indivisa in structure and ap- 

 pearance. All the tubular parts are white, the hydra red. The former, 

 that is the tube, occurs from the diameter of a horse's hair to the third or 

 fourth of a line ; and the latter from a mere speck to three lines in expan- 

 sion between the opposite tips of the tentacula. About 21 tentacula bor- 

 der the disc of the finest specimens ; the mouth is fringed by about 16 

 palpi, rough, rounder, and more obtuse than those of the Tuhularia indi- 

 visa. Faint whirls indent the neck of some specimens, and two of the 

 ramifications are sometimes united by a cross bar. 



Much irregularity subsists in aspect and proportions. Specimens 

 occur of all inferior dimensions to the largest instanced above, and of great 

 discrepancy in the proportion and number of parts. Specks scarcely 

 discernible by the naked eye are nearly white ; and others of very minute 

 dimensions which have only nine, or even but six tentacula. A stalk an 

 inch long frequently bears a head no larger than a branch extending three 

 lines from its side. Thus no definite rules seem applicable to the size, 

 proportions and appearance of this product. The lower parts are also 

 always so much interwoven, that, until cut out from among the rest, it is 

 impossible to determine the formation of a single specimen : Nor is it 

 easy to discover that only a single root is extricated. But the general 

 aspect and structure of the Tubularia may be seen in figs. 2, 3, 4. 



The polypus or hydra is not retractile within the stem, as there is no 

 vacuity in the summit for its reception. It is of a more lively nature than 

 the former, turning freely from side to side, closing and unfolding itself 

 repeatedly, and apparently enjoying a moderate degree of light. But both 

 are of that languid inactive disposition which constitutes a prominent fea- 

 ture of most zoophytes void of a receptacle for retreat and protection of 

 the head on the occurrence of danger. — Figs. 5, 6, enlarged. 



The propagation of this Tubularia resembles that of the indivisa in as 

 far as it can be ascertained. But the precise process is very rarely wit- 



