vol. 2, pt. 2.] A TAXONOMIC STUDY OF THE SALPIDAE METCALF. 79 



scuro. He mentions " a right and left longitudinal slip of unequal length 

 in connection with the two circumoral sphincters/' evidently meaning 

 that one "slip" is on the right and the other on the left. It seems 

 evident, however, from his figures, and from the relations in other 

 species between oral retractor and oral sphincter muscles, that we 

 have in Apsteinia asymmetrica a dorsal and a ventral division of the 

 oral retractor on each side of the body. The junction of the two 

 "slips" and their connection with the oral sphincters, which Fowler 

 figures, is not possible on any other interpretation. I have therefore 

 modified an obscure portion of his "Figure 8" [fig. 59, B] to show the 



A 



B 



Fig. 59.— Apsteinia asymmetrica embryo: A, from the right side; B, from the left side x 16 



DIAMETERS. FROM FOWLER (1896); B, SLIGHTLY MODIFIED. 



dorsal division of the oral retractor passing over the gill. Fowler's 

 "Figure 8," though obscure, seems to show the gill above the muscle 

 band. 



APSTEINIA ASYMMETRICA, aggregated form. 



The atrial siphon is asymmetrically placed (figs. 60 and 61). The 

 body muscles also are asymmetrical, their arrangement being rather 

 like that seen in the aggregated Apsteinia punctata. There are five 

 upon each side, muscles I, II, and III being asymmetrically in con- 

 tact dorsally. Muscle V shows the usual anterior and posterior 

 branches. Ventrally the intermediate muscle and all the body 

 muscles are interrupted except the two branches of body muscle V. 

 The ventral ends of the muscles of the right and left sides are very 

 asymmetrical, as shown in the figures. The gut is described as a 

 compact "nucleus." The condition of the eye and neural gland is 

 unknown. 



The resemblance between the aggregated forms of this species and 

 A2)steinia punctata, in the asymmetry both of the body and of the 

 body muscles, and the compact character of the gut in both solitary 

 and aggregated forms of Apsteinia asymmetrica, indicate that this 

 species should be placed among the Apsteinias rather than the 

 2621— Bull. 100, vol. 2—19 6 



