140 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



im. 



i.m. 



-/--m. 



musculature. His specimens of the aggregated zooids were clearly 

 of the bicaudata character, as is shown by his "Fig. 25, Taf. 3" (my 

 fig. 131, page 142), and they show considerable divergence from my 

 specimens in oral and atrial muscles. 



PEGEA CONFEDERATA, subspecies BICAUDATA, solitary form. 



I have had two specimens which may be of this form. One is 

 5 mm. long. This was given me long ago by Prof. W. K. Brooks. 

 Its source I do not know, nor do I know the authority for the label 

 bicaudata. The other embryo is 25 mm. long, but shows the eleoblast 

 still large. Both of these embryos agree in oral musculature with 

 Streiff's figures (bicaudata ?), but not in atrial musculature, in which 

 they agree with confederata. Assuming that Streiff's specimens, 

 though described as P. confederata, were really specimens of the 

 subspecies bicaudata, I am copying his figures, giving merely enough 

 description to call attention to the differences from Pegea confederata. 



Streiff describes the body 

 muscles as agreeing exactly 

 with those he describes and 

 figures for the aggregated 

 zooids (fig. 130, p. 142). 

 Their condition agrees also 

 with what I find in the body 

 muscles of Pegea confede- 

 rata. 



The intermediate muscle 

 (fig. 128) is as in my speci- 

 mens of Pegea confederata 

 (fig. 120,p. 132), except that 

 both its divisions are shorter 

 ventrally, ending some dis- 

 tance above the oral retrac- 

 tor muscles. 



Streiff says the oral musculature agrees exactly with that he 

 describes for the aggregated zooid (fig. 128). The divergence from 

 my specimens of the solitary Pegea confederata is slight but is notice- 

 able (fig. 120, p. 132). The oral retractor of bicaudata instead of 

 being divided into two, a dorsal retractor and a ventral retractor, is 

 divided into three horizontal bands, as in Thalia (fig. 105, p. 112). 

 The oral sphincters connected with them arc as in my specimens of 

 Pegea confederata. 



The atrial musculature described and figured by Streiff (fig. 129) is 

 decidedly different from what I find in all of my specimens. I will 

 not attempt even to indicate the homologies between the muscles in 



'z*/:; 



Fig. 128.— Pegea confederata, subspecies bicaudata, 

 oral muscles of either solitary or aggregated 

 form, seen from within. from streiff (1908). 



