ORDERACTINOIDEA. 43 



tentacles are tubular, and expansion takes place, as in the species 

 before described, by means of water, received from without, and 

 injected into these organs and other parts of the animal. The 

 Tubipore secretes a calcareous tube, or corallum, which is stiff and 

 firm below ; but near the extremity it is still tiexible, and the animal 

 contracts by drawing its head and tentacles into the tube, like turn- 

 ing in the end of the finger of a glove. Figure lb represents one of 

 the contracted animals, with the tube laid open by a longitudinal sec- 

 tion, showing the interior structure. The pear-shaped part above con- 

 tains the withdrawn and contracted tentacles; and the dark spots, near 

 the bottom of the same, are the openings into four of the tentacles, by 

 which water enters from the visceral cavity, when the animal expands 

 itself. 



37. The visceral cavity is long, tubular, and contains eight fleshy 

 lamellae. These lamellae aid, by their muscles, both in the contraction 

 and expansion of the polyp, in a manner which will be understood 

 without explanation, by a glance at figure lb. The stomach is cylin- 

 drical and very short compared with the whole length of the visceral 

 cavity; and, as in the preceding species described, it is connected with 

 the sides of the cavity by the visceral lamellae. 



Six of these lamellae were spermatic, being bordered below by the 

 white convoluted cord, while the other two gave origin to large 

 clusters of milk-white ovules, which occupied nearly the whole dia- 

 meter of the cavity. These ovules were of various sizes, and sphe- 

 rical in shape, or nearly so. Figure lb shows their position in the 

 tube, and Ic the appearance in profile of one of the lamellae with the 

 attached ovules. 



Some observers have found all the lamellae bordered with the white 

 filament, and others describe them as all bearing clusters of ovules. 

 In these instances, it would seem that the sexes were distinct, in one 

 case the animal being male, and in the other female. The subject 

 requires farther investigation. 



In the characters of the Tubipore we have the characters of the 

 Alcyonaria generally, a large tribe of zoophytes. The eight fringed 

 tentacles, and the eight visceral lamellae attaching the stomach to the 

 sides of the cavity, and extending below to the bottom of a tubular 

 visceral cavity, distinguish them at once from other Actinoid polyps. 

 The ovules in some species have been seen to escape by the mouth, 

 and this therefore appears to be the general mode m all the Acti- 



