1012 The American Naturalist. [November, 
habited by fresh water animals, such as Daphnids, ete.; this water is 
brought to the lake by streams from a neighboring marsh. Under 
the superficial layer of fresh water is found salt water, supporting a 
Marine fauna—-Sponges, Sea-anemones, Nemertines, Polychetes, 
marine Molluses, Starfish and Pantopods. There is even a regular lit- 
toral zone beneath the fresh water, characterized by small Fuci. 
The bottom of this lake is covered with mud exhaling an odor of 
sulphurretted hydrogen, and is not inhabited. The water of the lake 
shows a slight ebb and flow, attaining a vertical height of only a few 
inches, while the tides in the adjacent sea are considerably greater. 
This fact would appear to point to the existence of some subterranean 
communication between the lake and the sea. (Nature, July, 1895.) 
Sexual Rights and Lefts.—The genus Anableps includes sev- 
eral species of the most extraordinary of the fishes. With other novel 
characters, they have the eye divided into a lower section, looking 
downward, and an upper protruded above the head conveniently for 
seeing on the surface of the water; the pelvis also is divided; and the 
young are retained in the ovary until well developed. Our present, 
interest, however, concerns only their means of fertilization. Ina 
study of the Cyprinodonts (Monograph published as Vol. XIX, No. 1, 
of the Memoirs of the Museum of Comparative Zoology, from which 
this item is repeated) particular examinations of the anal fin of the 
males, which is modified into an intromittent organ, disclosed the fact 
that its structure adapts it for sidewise motion, rather than vertical. 
Directing attention to the species A. anableps of Linné (A. tetrophthal- 
mus of others), comparisons of the males showed that this organ differs 
in individuals, being functionally dextral on about three-fifths, and 
sinistral on about two-fifths of the specimens. Among the females in 
the Museum’s collection a similar state of affairs exists, but with the 
numbers reversed, two-fifths of them being rights and three-fifths lefts. 
Once possessed of the facts, dextrals and sinistrals are easily recog- 
nized. Happily Professor Agassiz, on his Brazilian Expedition, had 
provided a considerable amount of material to compare. 
Of the accompanying diagrams, figure 1 represents the lower side of 
the hinder portion of a dextral male, figure 2 that of a sinistral female, 
figure 3 that of a dextral female, and figure 4 that of a sinistral male. 
In its posterior half the anal fin of the male ( p ), the sexual organ, is 
bent to the right on dextrals (1), or to the left on sinistrals (4) ; it has 
on the convex side of the bend a small fleshy tubercle or gland (ce), 
while the urogenital tube lies along the concave side. The opening to 
