130 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



Cat. No. 6603, U.S.N.M. (aggregated form), Albatross station 

 D. 5320, China Sea, vicinity Formosa; November 6, 1908; surface; 

 surface temperature, 80° F.; 1 specimen. 



Cat. No. 6604, U.S.N.M. (large embryo and small), Albatross sta- 

 tion D. 5540, between Negros and Siquijor, Philippine Islands; 

 August 19, 1909; surface; surface temperature, 83° F.; 25+ speci- 

 mens. 



Cat. No. 6605, U.S.N.M. (aggregated form), Albatross station 

 D. 5140, vicinity of Jolo, Philippine Islands; February 14, 1908; 

 surface; surface temperature, 80°-82° F.; surface density, 1.02477: 

 5 specimens. 



Cat. No. 6606, U.S.N.M. (aggregated form), Albatross station 

 D. 5232, between Bohol and Leyte, Philippine Islands; May 7, 1908; 

 surface; surface temperature, 84° F.; surface density, 1.02531; 3 

 specimens. 



Cat. No. 6607, U.S.N.M. (aggregated form), Albatross station 

 D. 5456, east coast of Luzon, San Bernardino Strait to San Miguel 

 Bay, Philippine Islands; June 7, 1909; surface; surface temperature. 

 86° F.; 10 + specimens. 



Cat. No. 6608, U.S.N.M. (aggregated form and one large embryo), 

 Bubuan Island anchorage, Philippine Islands; February 14, 1908; 

 surface ; 47 + specimens. 



The musculature of this species is less developed than in any other 

 of the Salpidae except Traustediia. 



PEGEA CONFEDERATA, solitary form. 



In the solitary form there are four muscles which should be classed 

 as body muscles, two in front and two posterior, arranged as shown 

 in figure 119. The fifth muscle on the dorsal surface is probably the 

 homolog of the basal atrial sphincter in other species. All these 

 muscles are confined to the dorsal surface. They do not reach even 

 well onto the sides of the body. There is an intermediate muscle 

 (fig. 120) which, as in Thetys vagina (fig. 115, p. 123), fimctions in 

 connection with the oral muscles rather than the body muscles. It 

 is divided lengthwise into an anterior and a posterior band, which 

 are parallel. The dorsal horizontal band on each side is continuous 

 posteriorly with the anterior band of the intermediate muscle. In 

 front it is near to but not in contact with the broad sphincter of the 

 dorsal lip. 



The oral musculature (fig. 120) shows a retractor muscle which is 

 divided into dorsal and ventral divisions, the dorsal division having 

 two branches anteriorly. The ventral retractor connects anteriorly 

 with the broad sphincter of the upper lip, the only complete sphincter 

 in this lip. It connects also with the third sphincter of the lower 



