88 University of California Publications in Zoology [ VoL - 19 



sails on through the water with great swiftness in either the horizontal 

 or the vertical direction. From time to time when the motion becomes 

 slower a new jerky flapping of the wings occurs, increasing thus the 

 speed of locomotion to the original strength. Occasionally it rests 

 motionless at the surface of the water with its wings widely spread, 

 but the least disturbance of the water arouses the animal to sudden, 

 new activity. Judging from the laboratory observations the pteropod 

 seems to be in the habit of attaching itself to objects by means of the 

 epipodial tentacles, standing then in an erect position and flapping its 

 wings. "When placed in a shallow dish, the mollusc, after some floating 

 and swimming, usually attaches itself by its tentacles to the bottom 

 of the dish, in the meantime gracefully moving its large wings. The 

 latter operation is of some interest, considering the fact that the home 

 of the genus Desmopterus is predominantly the high sea, where objects 

 of attachment, except for a few floating weeds or some swimming 

 animals, are not usually common. The fact that the animal balances 

 its body so well while standing in an erect position for some time, 

 suggests the possibility that this practice is not new to it but that it 

 is an established adaptation. The observations are not sufficiently 

 numerous to justify any definite conclusions. An abundance of living 

 material would make possible some interesting observational studies. 

 On account of the transparency of the cuticle all the internal 

 organs can be readily seen at work in the living animal. As soon as 

 the animal dies the body tarns opaque and only the solid, external 

 form of the body and the large nerves of the wings are visible. 



LITERATURE CITED 



Chun, C. 



1889. Bericht iiber eine nach den Canarischen Inseln im Winter ausgefiihrte 

 Keise. Sitzungsber. Preuss. Akad. Wiss., Berlin, 29, 519-553, 1 pi. 



Meisenheimeb, J. 



1904. Zur Anatomie und systematischen Stellung von Desmopterus papilio 



Chun. Zool. Anz., 27, 331-335, 4 figs, in text. 

 1911. Pteropoda. Wiss. Ergeb. der deutschen Tiefsee-Expedition, 9, 1-314, 



35 pi., 9 charts, 37 figs, in text. 



Pelseneek, P. 



1889. Sur la position systematique de Desmopterus papilio Chun. Zool. 

 Anz., 12, 525-26. 



