189o.] Zoölogy. 965 
seen, and larger than any recorded by Prof. Leidy in his work on the 
** Fresh-Water Rhizopods of North America." The first specimen I 
measured, in place of being o.4 mm., the maximum diameter given by 
Leidy, was 0.85 mm. in diameter, with rays projecting 0.45 mm. be- 
yond the margin of the body. There are scores of individuals in my 
jar, and the average diameter is in excess of 0.75 mm. The largest 
specimen measured had a diameter of 1.36 mm., and there are not a 
few individuals that seem to be equally as large. 
It is worthy of record that a large proportion of the specimens that 
passed under the microscope had been feeding on small specimens of 
Cyclops. Rotifers seems to be a favorite article of diet with Actino- 
spherium, and even the individuals that had succeeded in capturing 
Cyclops contained often three or four Rotifers. Difflugia was taken 
by a few, but none, so far as observed, had condescended to feed on 
diatoms or other forms of algz. It has been a matter of surprise that 
a creature so sluggish as Actinosphzerium should be able to capture 
Cyclops. How the capture is made I have thus far not been able to 
determine.—S. CALVIN, Biological Laboratory, State University of Iowa, 
September 20, 1890. 
Portuguese Man-of-War.—Mr. Robert P. Bigelow studied * the 
habits of the Portuguese man-of-war (which has lost its familiar name 
Physalia arethusa, and has been rechristened Caravella maxima in 
Haeckel’s recent monograph). This form feeds largely on small fish ; 
these, swimming against the tentacles, are caught and benumbed ; but 
apparently their struggles pull the tentacle, which contracts, bringing 
the prey up to the numerous feeding-bells. If the fish does not 
struggle the tentacle fails to contract. The feeding-bells spread them- 
selves over the fish and digest it. During the summer of 1889 these 
splendid siphonophores were very abundant at Woods Holl, Mass., 
but during the summer of 1890 not a single individual was seen. 
Dimorphism in Antipatharia.—G. Brook describes? an inter- 
esting type of dimorphism in the Antipathide. In Schizopathes, 
Bathypathes, etc., the zooids have become elongated in the transve 
axis, so that the six tentacles appear like three pairs. Corresponding 
with this there is a depression between the oral and lateral regions, so 
that from the surface each zooid appears like three lobes, each with a 
pair of tentacles. Internally the lateral portions are separated from 
the central by a mesoglceal partition, and since the lateral mesenteries 
* Johns Hopkins Univ. Circ., IX., p. 61. 1899. _ 
5 Proc. Roy. Soc. Edinburgh, XVI., p. 78. 
