84 LOPHOPUS CRYSTALLINUS. 



1820. Plumatella cristata. Schweigger, Handbuch der Naturg., p. 424. 



1821. Naisa reptans. Lamouroux, Exp. Metli., p. 16, tab. 6S, figs. 3, 4. (Figures 



copied from Trembley.) 

 1824. Naisa reptans. Deslongchamps, Encyc. Meth. Zooph., 1824, p. 561. 

 1826. Plumatella cristata. Blainville, Diet. Sci. Nat., torn, xlii, art. Plumatella. 

 1828. Alcyonella, tertius evnlutionis gradus. Raspail, Hist. Nat. del' Ale. Fluv., Mcin. 



de la See. d'PIist. Nat. de Paris, vol. iv, p. 129. 



1834. Plumatella cristata. Blaiuville, Mau. d'Aetiu., p. 490. 



1835. Lophopus cr?/stullinus. Duraortier, Bull de I'Acad. de Brux., 1835, p. 424, 

 ' pi. 5, 6. (Original figures.) 



1836. Plumatella cristata. Lamarck, An. sans Vert., 2d edit., vol. ii, p. 122. 



1837. Plumatella camimnulata. Gervais, Ann. Sc. Nat., 2d ser., tom. vii, p. 78. 



1838. Alcyonella stagnorum. Johnston, Brit. Zoopli., 1st edit., p. 311, fig. 48, p. 314. 



(Figure copied from Trembley.) 



1839. Plumatella crystallina. Gervais, Ann. Franf. et Etrang. d'Anat., tom. iii, 



p. 134. 

 1844. Alcyonella stagnorum. Allman, Ann. Nat. Hist., vol. xii, p. 330. 



1847. Alcyonella stagnorum. Johnston, Brit. Zooph., 2d edit., p. 391, fig. 73, 



p. 395. (Figure copied from Trembley.) 



1848. Lophopus crystallinus. Van Beneden, Sur les Bryoz. fluv. de Belg., p. 23, 



Mem. de I'Acad. Roy. de Belg. 



1848. Lojihajms Bakeri. Van Beneden, Sur les Bryoz. fluv. de Belg., p. 24, pi. 2, 



Mem. de I'Acad. Roy. de Belg. (Original figure.) 



1849. Lopihopus crystallinus. Allman, Rep. Brit. Assoc., Trans, of Sect., p. 72. 



Iconof/raphy. — The original figures are those of Trembley, Baker, Shaw, Dumortier, and 

 Van Beneden. 



Habitat. — In ponds and ditches, where it attaches itself to the submerged parts of 

 Lemna, Sparganium, and various other aquatic plants, avoiding exposure to bright sun- 

 light. 



Localities. — British : Abundant in a millpond near Little Baddow, Essex ; a pond in 

 the Zoological Gardens, Dublin ; abundant. G. J. A. — In the water by the side of the 

 ^Yillow-walk, Chelsea, and in various waters in the neighbourhood of London. Shaw. 

 Foreign: Holland. Trembley. — Belgium. Dumortier and Vmi Beneden. 



When removed from the water, L. crystallimis appears immersed in a transparent 

 gelatinous investment which envelopes the entire colony, leaving only the orifices free. This 

 investment, which, as has been already shown,* is really a delicate transparent membrane 

 filled with a fluid and representing the ectocyst, may be easily removed ; and, indeed, specimens 

 kept for some time in confinement may often be found quite freed from it. I cannot help 

 thinking that the specimens observed by M. Van Beneden, and described by this naturalist 

 as destitute of the investment in question, were only accidentally in this state, Avhich I believe 

 is never presented by freshly captured, healthy individuals. 



* Vide supra, p. 14. 



