UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



ZOOLOGY 



Vol. 19, No. 2, pp. 85-88, 2 figures in text May 9, 1919 



THE PTEROPOD DESMOPTERUS fa 



PACIFIGUS SP. NOV. 



CHRISTINE ESSENBERG 



Nearly thirty years ago a new pteropod was discovered and de- 

 scribed by Chun. This beautiful animal differed so greatly from any 

 other pteropod that it did not fit hi any of the larger subdivisions of 

 that group and consequently was an object of dispute among the 

 authors as to the place it should take in the classification. Chun (1889) 

 named the mollusc Desmopterus papilio, placing it with the Gymno- 

 soma on account of the absence of a shell. Pelseneer (1889) classified 

 Desmopterus with the Thecosoma, putting it as a genus in the family 

 Cymbuliidae. Meisenheimer (1904) in his revision of the Pteropoda 

 separated the new genus from the Cymbuliidae and elevated it to the 

 rank of a separate family, the Desmopteridae. 



Meisenheimer (1904) gave a distribution of the group as it was then 

 known. Reference is made to only one species, Desmopterus papilio. 

 According to that report the genus is limited in its distribution to the 

 tropical and sub-tropical zones, occurring on the entire African coast 

 between 34° N and 37° 5' S lat., in the Mediterranean Sea, and in the 

 Indian Ocean. In this ocean the distribution is strictly limited to the 

 tropical zone (between 11° S and 13° N lat.). It is of interest to note 

 that no Desmopteridae have been reported from American waters. 

 Hence the species described on the following pages is the first repre- 

 sentative of the group to be made known either from the Pacific or 

 the Atlantic waters of America. The description of the present species 

 is based on twenty-seven individuals. Two of these were taken in the 

 surface plankton nets at the Scripps Institution for Biological Research 

 of the University of California, 32° 53' N lat., 117° 15' 7" W long, on 

 two successive mornings, December 7 and 8, 1917. Other specimens 

 were taken by the United States Bureau of Fisheries steamer Albatross 



