426 Wisconsin Academy of Sciences, Arts, and Letters. 
KAESCH, A. F. F., 1846. Die Entwicklungsgeschichte des Limnaeus stag- 
nalis, ovatus und palustris, nach eignen Beobachtungen dargestellt.—Arch. 
Naturg., Berlin, Jahrg. 12, vol. 1, pp. 236-276, pi. 9. 
ECKEE, A., 1851. Zur Entwickelungsgeschichte der Infusorien.—Zeitschr. 
Wis. Zool., vol. 3, pp. 412-415; Froriep’s Tagesber. Fortschr. Nat.-u. 
Heilk., Abt. Zool., vol. 2 (for 1852), pp. 273-275. 
We have not seen the living animal; the foregoing description 
is from material kindly furnished us by the late Mr. John Stevens, 
of Exeter, England, who gave the first adequate account of this 
species. The free-swimming young female pierces the shell of the 
snails’ egg, feeds on the contents and lays its eggs within the shell,, 
where the young continue the destruction of the embryo snail. 
The fully grown female Proales gigantea is very much larger than 
in the free-swimming stage, reaching a size of fully 500/x, and be¬ 
comes a shapeless, distended bag, hardly recognizable as a rotifer. 
A full account,of the development of the eggs is given by Stevens. 
PROALES WERNECKII (Ehrenl)erg). 
Plate XVII, figures 1-5. 
Cyclops lupula Vaucher, Hist. Conf. d’Eau Douce, 1803, p. 18, pi. 3, figs. 8r,. 
11s; not Cyclops lupula Muller. 
Notommata wernecTcii Ehrenberg, Abh. Akad. Wiss. Berlin (for 1833), 1834,. 
p. 216; Infusionsthierchen, 1838, p. 429.— Oliver, Trans. Tyneside Nat. 
Field Club, vol. 4, 1860, p. 263, pi. 14.— Magnus, Verb. Botan. Ver. Prov. 
Brandenburg, vol. 18, 1876, p. 125.— Wollny, Hedwigia, vol. 16, 1877, p. 
163; vol. 17, 1877, pp. 5, 97.— Balbiani, Ann. Sci. Nat., Zool., ser. 6, vol. 7,. 
No. 2, p. 1, pi. 4, figs. 1-18; Journ. Eoyal Micr. Soc., 1879, p. 530, pi. 18.— 
Hudson and Gosse, Eotifera, 1886, vol. 2, p. 134.— Debray, Bull. Sci. 
France et Belgique, vol. 22, 1890, p. 222, pi. 11.— Eothert, Zool. Jahrb.,. 
Syst., vol. 9, 1896, p. 673, figs. A-D; Jahrb. Wiss. Bot., vol. 29, 1896, p., 
525, pis. 8, 9. 
Copeus wernecTcii Ehrenberg, Infusionsthierchen, 1838, p. 441. 
Proales wernecTcii Hudson and Gosse, Eotifera, Suppl., 1889, p. 23, pi. 32,, 
fig. 18. — Eousselet, Journ. Quekett Micr. Club, ser. 2, vol. 6, 1897, p. 415,. 
pi. 19, figs. 1-4. — Lucks, Eotatorienfauna Westpreussens, 1912, p. 52, fig. 
8. —Voigt, Siisswasserfauna Deutschlands, pt. 14, 1912, p. 89, fig. 157.— 
Weber and Montet, Cat. Invert. Suisse, pt. 11, 1918, p. 102, fig. 29. 
The body of the free-swimming female is elongate, spindle- 
shaped and very slender, its greatest width is about one sixth of 
the total length. The integument is very flexible and the outline 
constantly changing. The body is very transparent. 
The head segment is considerably longer than wide; it is rounded 
anteriorly, and this portion is separated from the head proper by 
