86 University of California Publications in Zoology [Vol. 19 



on July 28, 1916, at 32° 36' 5" N lat. and 118° 7' W long, at stations 

 6684, 6686, 6687, and 6689 in the self-closing nets at the depth of 

 fifty meters. 



Description of the Species 



Desmopterus paeificus is one to two millimeters long, and four to 

 five millimeters wide, measured from tip to tip of the spread wings. 

 The body (fig. 2) is somewhat barrel-shaped. The anterior or the head 

 end is bent ventrad. The shell is absent, but the body is covered com- 

 pletely by a transparent integument. The strongly developed wings, 

 the epipodia, are attached to the anteroventral portion of the body and 



Fig. 1. Ventral view of Desmopterus papilio after Chun, greatly enlarged; 

 e.t., epipodial tentacles. Note the sharply bent head and the long wings. 



are fused in the middle. Their posterior margin extends beyond the 

 posterior extremity of the body. It is deeply indented, the entire 

 margin being divided into five distinct lobes (fig. 2), one median, and 

 two lateral on each side. The anterior margin of each wing is only 

 slightly curved and is without indentations or lobes. Between the two 

 lobes of the posterior margin of each wing are inserted the epipodial 

 tentacles (fig. 2, e.t.). These are short, their length being only one 

 and one-half times their width. Each tentacle is supplied with a strong 

 nerve and is covered with cilia. Judging by the rich nerve supply these 

 tentacles are sensory, probably tactile organs. The wings are supplied 

 with well developed nerves. One strong nerve is sent to each lobe, 

 subdividing and spreading there into several smaller branches, and 

 one large nerve goes to each epipodial tentacle. 



