77 



5. 



Diagnosis, Synonymy, and Natural History of the Genera and Species. 



CRISTATELLID^. 

 Genus I. Cristatella, Cuvier, 1798. 

 Name. — A diminutive noun formed from crista, a crest, in allusion to its tentacular plume. 



The genus Cristatella was established by Cuvier, for the little animal originally described 

 by Eijsel under the title of " Der Kleinere Federbusch Polyp mit dem ballenformigen 

 Korper." Its characters were given in the ' Tableau Elementaire des Animaux,' published 

 in 1798, and it is the first generic group constituted for any of the fresh-water Polyzoa, 

 hitherto all confounded together in discordant and unzoological associations. Rosel's animal, 

 however, was unknown to Cuvier, except from the figures and descriptions left us by its 

 discoverer ; and it was not until Turpin and Gervais many years afterwards rediscovered it, 

 having hatched it from statoblasts found in the Canal d'Ourcq, in the city of Paris, that any 

 additions were made to the original account left us by Eosel. Still, however, nothing was 

 known of the animal but in its young and partially developed state, and it was only afterwards, 

 when adult and fully formed specimens were met with, that the real nature of this beautiful 

 Polyzoon was properly understood. 



The genus, which includes as yet but a single species, may be thus characterised : 



Generic character. — Coenoecium sacciform, hyaline, with a common flattened discadapted 

 for locomotion ; orifices placed on the surface opposite to the disc, and arranged in several con- 

 centric marginal series. Statoblasts orbicular, with an annulus and marginal spines. 



Species unica. Cristatella mucedo, Cuvier. PI. I. 

 Specific character. — Same as that of the genus. 



Synonyms. — 1755. Ber Kleinere Federbusch-Polyp. Eosel, Insect. Belustig. Supp., p. 559, 

 tab. 91. (Original figure.) 

 1766. La seconde sorte de Pobjpes a Bouquets. Ledermuller, Amusm. Mic. 2''''cinq., 



p. 94, pi. 87. (The figures are imperfect copies from Rosel.) 

 1798. Cristatella mucedo. Cuvier, Tab. Elem., p. 656. 



1816. Cristatella vagans. Lamk., An. sans Vert., 1st edit., vol. ii, p. 97. 



1817. Cristatella mucedo. Cuv., Regne A., 1st edit., vol. iv, p. 68. 

 1820. Cristatella vagans. Schweigger, Ilandbuch der Naturg. p. 423. 



1824. Cristatella vayans. Lamouroux, Enc. Metli. Zoopli., p. 226, pi. 472. 

 (Figures copied from Rosel.) 



