52 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



The gut is figured by Traustedt (1893) as apparently a compact 

 "nucleus," but Apstein (1894, b) shows it in the embryo as a loop 

 (fig. 23), but more compact than in any Cyclosalpa. 



BROOKSIA ROSTRATA, aggregated form. 



The aggregated form of Brooksia rostrata has been described only by 

 Apstein (1894, b). It shows (fig. 24) about as much asymmetry 

 as the aggregated Gyclosalpa virgula. The pattern of the asym- 

 metry is constant, except that in some individuals it is exactly re- 

 versed. According to Apstein's description, in a dextral zooid, there 

 are four body muscles on the right side and three on the left, as is true 

 of the aggregated Cyclosalpa virgula. On the right side the interme- 



cn. 



en. 



i.rrv. 



a b r 



Fig. 24.— Brooksia rostrata, aggregated zooro: A, ventral view; B, view from left side; C, 



DORSAL VIEW. X 40 DIAMETERS. FROM APSTEIN (1894, b). 



diate muscle and body muscles I and II are united, or at least in con- 

 tact, dorsally, as in Cyclosalpa virgula. Muscle III joins muscle II 

 much as it would in C. virgula if the muscles were crowded toward the 

 mid-dorsal point, as is the case in at least the young zooids of Brooksia 

 rostrata. Body muscle IV is similarly drawn forward, as contrasted 

 with the condition in Cyclosalpa virgula. From muscle IV, on the 

 right side, there is a branch (IV, b) running to near the base of the gut. 

 On the left side of Brooksia rostrata there are three recognizable body 

 muscles, as is the case on both sides of the aggregated Cyclosalpa 

 floridana, in which species, as we have suggested, body muscles I and 

 II may be fused. The body muscles of the aggregated Brooksia 

 rostrata are thus seen to be of the Cyclosalpa type. 



Apstein figures the eye, but not in sufficient detail to avail for com- 

 parisons. If he shows accurately the disposition of the pigment, the 

 eye of the aggregated form of this species is different from that of any 

 other known species.* 



