vou2.pt. 2.] A TAXONOMTC STUDY OF THE SALPIDAE METCALF. 141 



the two forms, except in the case of the atrial retractor and the fourth 

 body muscle, which I label in his figure, to aid in orienting it in com- 

 parison with niy figure 122. The differences here would seem almost 

 to deserve emphasis as of specific value. It seems probable that 

 Streiff's specimens were bicaudata and that both of my possible 

 bicaudata embryos are really confederata, though one bears the label 

 bicaudata and the other is in a phial with two aggregated bicaudata 

 and one aggregated confederata. The solitary form of bicaudata 

 needs further study. 



PEGEA CONFEDERATA, subspecies BICAUDATA, aggregated form. 



I have had nine lots of alcoholic specimens of the aggregated zooids 

 of this subspecies, collected by the United States Bureau of Fisheries, 

 steamer Albatross, off 

 the eastern coast of the 

 United States between 

 Cape Hatteras and Cape 

 Cod, also three speci- 

 mens from the Naples 

 Zoological Station (U. S. 

 National Museum, Cat. 

 No. 6462). They show 

 the appendages, and the 

 eyes are of the bicaudata 

 type. Their musculature 

 also agrees with Streiff's 

 description. The de- 

 scription here given is 

 based chiefly on Streiff's 

 results, confirmed, how- 

 ever, from my material. 



The aggregated zooid 

 (fig. 130) is very similar to that of the typical Pegea confederata 

 but can be distinguished by several features: first, by the presence 

 of a pair of long postero-lateral tubular appendages; second, by 

 slight features in the character of the muscles of the oral region; 

 third by more marked divergences from the species proper in its 

 atrial musculature ; and fourth, by the stalked character of its large 

 dorsal eye. 



The body muscles are as in the aggregated Pegea confederata 

 proper. The intermediate muscle (fig. 128) is "as in the solitary" 

 bicaudata and the aggregated confederata (fig. 124), differing from 

 that of the solitary confederata (fig. 120) in being shorter, ending 

 some distance above the oral retractor. The dorsal horizontal band 

 with which it is continuous dorsally is as in the aggregated con- 

 federata, being longer than in the solitary confederata, reaching more 



~-a.r. 



Fig. 129.— Pegea confederata, subspecies bicaudata, soli- 

 tary FORM, CLOACAL MUSCLES: d. m. I., DORSAL MID LINE; 

 v. m. I., VENTRAL MED line. From Streiff (1908). 



