678 THE AMERICAN NATURALIST. | [Vor. XXXIV. 
i 
Species of Hygroceleuthus and Dolichopus," with remarks on Hygro- 
celeuthus by A. L. Melander and C. T. Brues; “On the Origin of 
the Sperm Blastophore of Some Aquatic Oligocheta,” by S. Hatai ; 
* Peculiar Tracheal Dilatations in Bittacomorpha clavipes Fabr.," 
by C. T. Brues ; and * Lampreys in Captivity," by A. M. Reese. 
BOTANY. 
Alternation of Generations in Alga.! — The author has made a 
careful study of the European forms of the .Cutleriacez, a small but 
interesting group of alga, and the results are given in this paper of 
one hundred pages. Two genera have been known in European 
waters, Zanardinia and Cutleria, the former represented by a single 
species, Z. collaris, the latter by two, C. mu/tifida and C. adspersa. 
Each is represented by a sexual and an asexual form, in Zanardinia 
indistinguishable in habit, but in Cutleria so different that the asexual 
form was long known as a separate genus, Aglaozonia. 
The paper begins with a thorough résumé of the previous investi- 
gations by Thuret, Reinke, Falkenberg, Janczewski, Kuckuck, and 
Church, which showed Aglaozonia to be included in the Cutleria 
cycle of development, assigning to C. multifida, A. parvula, and to 
C. adspersa, A. chilosa. The author has discovered a new form, 
A. melanoidea, occurring in the Mediterranean and on the Atlantic 
coast of Morocco, thus giving three sexual to two asexual forms. 
Though absolute proof has not been obtained, the author seems jus- 
tified in regarding the new form as connected with C. adspersa, the 
sexual form corresponding to A. chilosa being yet to be discovered. 
As the asexual form of C. multifida has a farther range northward 
than the sexual form, it is not improbable that the sexual form of 
A. chilosa may be some little known tropical or subtropical species. 
In studying the fertilization and development of Cutleria we find 
a curious complexity. The sexual form is dicecious; in many locali- 
ties only the female plant is known, propagating freely by partheno- 
genesis; in some localities male plants are extremely rare; in others 
they occur in equal numbers with the female, or are even twice as 
common; but in only one place have cultures shown fecundation of 
the oóspore. In the locality where the male plant is most abundant 
1 Sauvageau, Camille. Les Cutlériacées et leur alternance de Générations, 
Ann. Sci. Nat., Ser. 8, Botany, vol. x, pp. 265-362. . 
