—_—— 
PTEROPODA. AR5 
PTEROPODA. 
Tue following species of the order Pteropoda are here given, with 
a strong impression that some of them may have been described. But 
they are not satisfactorily identified with any figures of species I have 
seen. Indeed, with the exception of those given by D’Orbigny in his 
Voyage dans l Amérique Méridionale, and by Eydoux and Souleyet 
in the Voyage of the Bonite, no figures or descriptions of any value 
have been furnished. These animals are seldom to be obtained except 
in the open sea, and require to be immediately figured by a skilful 
hand, with the aid of a microscope. Of course, very few have fallen 
under the eye of competent observers. Every addition to the know- 
ledge of the general or detailed forms of this little-understood group 
of minute and beautiful objects, will be of service in the future dispo- 
sition of its members. 
The figures made by Mr. Dana evince careful observation and 
faithful delineation, and may be relied on as characteristic. 
LIMacINa SCAPHOIDEA (Gould). 
T. pellucida, involuta, scaphoidea: sptra secunda, anfractibus tribus ; 
ultimo amplo; apertura subeircularis ; labro arcuato. 
Ayimat having the alar expansions elongate, obliquely rounded at 
tip, broadly united at base, and standing off from each other obliquely 
at an angle of ninety degrees. At their junction are two papille, each 
surmounted by a black spine or beak. 
SHELL involute or nautiloid, the spire inclined to one side, exhibit- 
ing three whorls on the projecting side; the last whorl is very capa- 
cious, having the aperture rounded, and of nearly equal diameters ; 
the lip seen in profile is concavely arcuate. 
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