204 Proceedings of the 



into small four-tentacled polyps (fig. 9), and protruded creep- 

 ing tubes from their base,— the rudiments of the future poly- 

 pary. 



29. Quatrefages has figured the male or sperm capsule of 

 Hydractinia, and mistaken it for a reproductive " bulbil." 

 Johnston also falls into a similar blunder. Van Beneden, 

 again, has described the male and female polyparies as dis- 

 tinct species, under the name of Hydractinia lactea and 

 rosea. 



30. The Ophidian, or Spiral Polyps (fig. 1 a, fig. 10, and 

 fig. 13 a). I can scarcely express. the surprise I felt on dis- 

 covering these remarkable organs. I was examining a speci- 

 men of Hydractinia, from which the crab had been removed, 

 when I found a number of bodies, like small white snakes, 

 closely coiled in one, two, or three spirals, and grouped imme- 

 diately round the mouth of the shell (fig. 13 a). These 

 bodies, when touched, only drew their folds more closely 

 together. But if any part of the polypary, however distant 

 from them, was irritated, the spiral polyps uncoiled, ex- 

 tended, and lashed themselves violently backwards and for- 

 wards, and then quickly rolled themselves up again; and that 

 not irregularly or independently of each other, but all together, 

 and in the same direction, as if moved by a single spring. A 

 violent laceration of the polypary caused these polyps to re- 

 main extended and stretched like a waving and tremulous 

 fringe across the mouth of the shell for several minutes. The 

 Ophidian Polyps (evidently a barren modification of the re- 

 productive polyp) are never found in any other situation on 

 the polypary than in that before described, or round the 

 margins of accidental holes in the shell. They have no 

 mouth, and the tentacles are rudimentary. The walls of the 

 body are very transparent, from the extreme vacuolation of 

 the endoderm. The muscular coat, as might be expected 

 from the active movements of the polyps, is highly developed, 

 and forms a beautiful object on the dark polarized field of 

 the microscope, each spiral coil shining out as a bright double 

 ring, divided by four dark sectors. The ectoderm of the 

 whole body and tentacles is crowded with the larger thread- 

 cells. The ophidian polyps are, I doubt not, organs of de- 



