150 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [444] 
the surface of the water. ‘‘ During the day they often remain sus- 
pended for hours in the water simply by spreading their wing-like ap- 
pendages, and then suddenly drop to the bottom on folding them.” Mr. 
Agassiz captured the specimens upon which his observations were made, 
at Nahant, Massachusetts, during the summer of 1869, and judging 
from the figures in Binney’s Gould they were probably specimens, not 
quite adult, of this species. He has also taken adult specimens at 
Newport. Mr. 8. I. Smith captured full grown specimens in the edge 
of the Gulf Stream, off St. George’s Bank, and we have specimens taken 
from the stomach of mackerel, caught twenty miles south of No Man’s 
Land. 
The Cavolina tidentata (Plate XXV, fig. 177) isa beautiful and curious 
species, with a singularly shaped, amber-colored, translucent shell, much 
larger than that of either of the preceding species. We did not observe 
it living in these waters, but the shells were twice dredged off Martha’s 
Vineyard, and one of them was perfectly fresh and glossy, as if just 
dead. It is a southern species which comes north in the Gulf Stream, 
but it had not been found previously on the coast of New England. 
Another Gulf Stream species, the Diacria trispinosa, is occasionally 
found at Nantucket, according to Dr. Stimpson, but whether it has been 
observed there alive is uncertain; eight or nine other species were taken 
in the Gulf Stream, off St. George’s Bank, by Messrs. Smith and Har- 
ger in 1872, all of which may, perhaps, occasionally occur about Martha’s 
Vineyard and Nantucket. 
Another very interesting and beautiful Pteropod, the Clione papilio- 
nacea, was taken in considerable numbers at Watch Hill, Rhode Island, 
April 13, by Professor D. C. Eaton and myself. They were swim- 
ming at midday near the surface, associated with Pleurobrachia rhodo- 
dactyla, and appeared to be common at that time. Mr. Vinal N. 
Edwards obtained two specimens in Vineyard Sound, April 30. 
This differs from those named above, in being destitute of a shell. as 
well as in many other characters. The body is stout, somewhat fusi- 
form, tapering gradually to the pointed posterior end; in the largest 
specimens the length was about 1.5 inches. The head is rounded, with 
two small conical processes in front, on the upper side. Six tentacle- 
like organs, or ‘‘ arms,” bearing minute suckers, can be protruded. The 
wings or fins are large and broad oval in outline. 
The body and wings are pale, transparent bluish, with opalescent 
hues ; the mouth and parts around it, the “arms,” and part of the 
head, and some of the internal organs, are tinged with orange; the 
posterior part of the body is bright reddish orange, for nearly half an 
inch. Some of the internal organs are orange-brown and olive-brown, 
and show through the transparent integuments as dark patches. This 
species has seldom been observed on our coast. Dekay, in 1845, men- 
tioned its occurrence in a single instance, off New York. In 1869, it 
was taken in considerable numbers at Portland, Maine, by Mr. C. B. 
