Cristatella. 7. ASCIDIOIDA. 311 



are known to undergo somewhat similar changes. The eggs float 

 in the water from their lesser specific gravity, but often they be- 

 come attached by their spines to the filaments of confervae, <S:c. where 

 they float until the young are hatched and aff'ord to them an im- 

 mediate place of rest. 



M. Turpin has ascertained that some varieties of silex contain im- 

 mense numbers of the ova of the Cristatella and Alcyonella, preserv- 

 ed in entire perfection. Ann. des Sc. Nat. Part. Zool. vii. 120, 

 plates 6 and 7. 



43. Alcyonella,* Lamarck. 

 Character. Polypidom Jixed^ ina-ustingf or Jloating, in 

 the form of an irregular sponge-like mass composed of vertical 

 aggregated 7nembronaceous tubes opening on the surface. — Poly- 

 pes ascidian, the mouth encircled loith a single series offiUform 

 tentacula depressed or iricomplete on one side : eggs coriaceous, 

 smooth. 



1. A. stagnorum. 



Plate xliv. 



Variation *. Sponge-like, massive Alcyonium fluviatile, Bosc, Vers, iii. 



159. Corall. 250. Ephydatia Gibbsii, Gray, Brit. PI. i. 353 



Alcyonella stagnorum, Lam, Anim. s. Vert. ii. 102. 2de edit. ii. 116. 

 Stark, Elem. ii. 442. Lamour. Soland. tab. 76, fig. 5—8. (bad.) Teale 

 in Trans. Leeds Phil, and Lit. See. i. 116, pi. 12, and in Mag. Zool. 



and Bot. i. 293 A. fluviatilis, Raspail in M^m. de la See. d'Hist. 



Nat. de Paris, iv. 130, pi. 12 — 16. L' Alcyonella des etangs, Blainv. 



Actinolog. 491, pi. 85. fig. 8. 



Variation /S. Polypidom lohed or stellate — Polypes a panache, Tremb. Mem. 



210, pi. 10, fig. 8—9. Reaum. Mem. des Insect, vi. pref. Ixxvi The 



Bell- Flower- Animal or plumed Polype, ^aAer, Employ. Micros. 306, pi. 



12, fig. 15 — 22. Hydra campanulata, Zin. Syst. edit. 10, 817 



Tubularia erystallina, Pall. Elench. 85 T. campanulata, Lin. Syst. 



1303. Berk. Syn. i- 215. Shaw Nat. Misc. x. pi. 354. Turt. Gmel. iv. 

 668. Turt. Brit. Faun. 211. Adams on the Microscope, 449, pi. 22, 



fig. 32. Bosc, Vers, iii. 92. Blumenb. Man. 272 T. reptens, Bosc, 



Vers, iii. 93 Plumatella cristata. Lam. Anim. s. Vert. ii. 107. 2de 



edit. ii. 122. Stark, Elem. ii, 441. Blainv. Actinol. 490. PI. campa- 

 nulata, Risso, L'Euvop. Merid. v. 308 Naisa reptans, Corall. 99, 



pi. 6, fig. 4. Cristatella campanulata, Flem. Brit. Anim. 518 



C. paludosa, Dalyell in Rep. Brit. Assoc, an. 1834, 606. 

 Hab. Stagnant waters, especially in such as are tinctured with iron 



• A diminutive from Halcyon. The sponge -genus Alcyonelliim of Quoy and 

 Gaymard, being of subsequent creation, cannot be retained. 



