192 ZOOPHYTES. 



• 



sion of the parts, and it sometimes protrudes from the extremity. But 

 whether by an orifice there, is doubtful. It is somewhat under three 

 inches in length, about the fortieth part of an inch in diameter, generally 

 waving at the ends, and the lower extremity reduced to the slender- 

 ness of a hair. Its position and adherence within the shank are not well 

 understood. It rather seems as if the upper end were invested by the 

 flesh, though slightly, for it slips out of the shank as if quite free. How- 

 ever, the lower end is naturally hooked like a shepherd's crook, the curve 

 an eighth of an inch deep, narrow, and occupied by a whitish fleshy sub- 

 stance. 



I procured sixty-four specimens at once early in May. All excepting 

 twelve appeared to have been injured ; the bone was either broken, or it 

 protruded from the extremity of the shank. These specimens were in a 

 contracted state, but being disposed under suitable treatment in several 

 vessels, sufficiently replenished, the bone was next day retracted, and co- 

 vered by almost the whole ; and some of the specimens extended four 

 inches and a half. 



A considerable bulb is formed by the lower extremity, which, when 

 swollen, extends beyond the bone. It may be conjectured that this ex- 

 tremity is pierced by the bone on contraction, and that protrusion ensues 

 in consequence. But there may be a natural orifice. 



It is not evident that the Pennatula enjoys any proper faculty of pro- 

 gression more than the former. A great recurvature can be formed by the 

 upper part or feather, which the bone does not rise high enough to obli- 

 terate. The animal has also much controul over the dimensions, reciprocal 

 position, and direction of the lobes. Certain parts may be distended dis- 

 proportionately compared with the rest. All the hydra have separate and 

 independent action. But farther than complete distension of the whole 

 specimen, whereby its previous contracted dimensions may be quadru- 

 pled, no farther approximation to motion is betrayed. Neither does 

 such distension, though to the utmost, reduce its specific gravity sufficient- 

 ly to produce an equilibrium with the water. Thus the animal cannot 

 swim. Neither have I ever seen a reversed specimen, that is, laying flat 

 with the hydra? downwards, regain the natural position, which I conclude 

 is laying flat with the hydra? turned upwards. 



