Laomedea. Z. HYDROIDA. 15J 



in general, clothed with cilia and moveable. Every three of them 

 are inclosed, while in the vesicle, within a thin transparent motion- 

 less capsule, presenting at its free extremity several stiff, straight^ 

 diverging pointed processes, which Ellis mistook for the tentacula of 

 a young polypus. Dr Grant. 



Sir John G. Dalyell has made some singular observations on this 

 species, which seem irreconcileable with those of Professor Grant and 

 Cavolioi. He tells us that it rarely produces vesicles. When pre- 

 sent they contain from 20 to 30 greyish corpuscula with a dark cen- 

 tral nucleus. " At first, all are immature and quiescent, but motion 

 at length commences : the corpuscula become more distinct ; sevei'al 

 slender arms protrude from the orifice of the vesicle, which are seen 

 in vehement action, and, after many struggles, an animated being es- 

 capes. But this has no relation either to the planula of the Sertu- 

 larise, or the corpusculum of the Flustra, Alcyonium, or Actinia. It 

 might be rather associated with the Medusariai. Before ascertaining 

 its origin, I had named it Animalculum tintinnabuluvi, from its gene- 

 ral resemblance to a common hand-bell, for the purpose of recogni- 

 tion. This creature is whitish, tending to transparency, about half 

 a line in diameter ; the body is like a deep watch glass, surmounted 

 by a crest rising from the centre, and fringed by about twenty-three 

 tentacula pendant from the lip below. These are of muricate struc- 

 ture, or rough, and connected to the lip by a bulb twice their own 

 diameter. The summit of the crest unfolds occasionally into four 

 leaves, and four organs prominent on the convexity of the body, ap- 

 pear at its base. When free, the animal swims by jerks, or leaps 

 through the water, or drops gently downwards ; it is invited to move 

 by the light, and it has survived at least eight days. Then it disap- 

 pears, at least I have not been able to pursue its history longer. No 

 other product has ever issued from the vesicles of the Sertularia di- 

 chotoma." Edin. New Phil. Journ. xxi. 91-2. 



2. L. GENICULATA, stem zig-zag, simple or sparingly brandi- 

 ed ; cells on annular stalks from the joints, alternate, campanu- 

 late, the 7'im plain ; vesicles ovate. Doody. 



Plate XXI. Fig. 1, 2. 

 Corallina confervoides gelatinosa alba, gcniculis crassiusculis pellucidis, 



Baii, Syn. i. 34, no. 7. Fucoides setaceum tenuissime alatiini, Ibid. 



38, no. 6, pi. 2, fig. 2. Ellis, in Phil. Trans, abridg. x. 491, pi. 12, fig. 



1, a, A. Knotted-thread Coralline, Ellis, Corall. 22, no. 19, pi. 12. 



h. B Sertularia geniculata, Z/». Syst. 1312. Pull. Elencli. 117. 



Mull. Zool. Dan. tab. 117, fig. 1-4. Ellis awA Solund. Zooi)li. 49. Berk. 

 Syn. i. 218. Tiirt. Gmel. iv. 682. Weni. Mem. i. 564. Tint. Brit. 

 Faun. 215. .S^ew. Elem. ii. 446. ^osc. Vers, iii. 117. Z«»(. Anim. s. 



