174 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



a, 2 Aggregated zooids bilaterally asymmetrical, terminal zooids of stolon not 



known to be detached in whorls Cyclosalpae asymmetricales . 



a, 1 Body muscles in solitary form not forming any ventral horizontal bands: 

 postabdomen of aggregated zooid long and unequally bifurcate, the 

 larger division occupied by the intestine proximally and the slender 

 testis distally, the smaller division occupied proximally by the single 

 caecum and distally by a cell mass superficially resembling the testis. 



bakeri. 



a, 2 Certain of the bodjf muscles of the solitary form elongated to form a dorsal 



and a ven tralpair of horizontal bands: aggregated zooid with undivided 



postabdomen containing intestine and testis virgula. 



B. Gut in solitary forms not making a very compact nucleus. The course of the 

 intestine can be traced without dissection. In the aggregated zooids the gut 

 forms a "nucleus" in which, in most species, the course of the intestine can 

 hardly be detected by superficial observation. 

 Circodea. 



b, 1 Solitary form with a long anterior protuberance below the mouth, 

 containing wide muscle bands. Aggregated zooids very asymmet- 

 rical Broohsia. 



13, 1 One species rostrata. 



b, 2 Body muscles in the solitary form more than 10, asymmetrically con- 

 tinuous across the dorsal mid line Ritteria. 



/3, 1 Body muscles 15: aggregated zooids inadequately known, asymmet- 

 rical retracta . 



0, 2 Body muscles in the solitary form 21 or more: aggregated zooids 



unknown pictcti. 



/3, 3 Body muscles in the solitary form 11, not so wide as to form an almost 

 continuous layer; gut a transverse vertical loop: aggregated zooid 

 asymmetrical, its gut a close loop but with the course of the 



intestine visible (type) amboinensis. 



/3, 4 Body muscles in the solitary form very broad forming an almost con- 

 tinuous layer, especially posteriorly; a pair of postero-lateral 

 appendages present: aggregated zooid showing 6 well-marked 



longitudinal ridges; it has 6 broad body muscles hexagona. 



b, S Solitary form with 5 pairs of very broad muscle bands and a narrower 

 shorter 6th on the dorsal surface behind them, body terminating behind 

 in a sharp point whose enlarged base contains the gut; atrial aperture 

 a horizontal slit. Aggregated zooid with similar atrial aperture, 3-5 

 embryos, 5 strong body muscles, nearly parallel, all but the first con- 

 tinuous across the mid-dorsal line, body pointed behind and narrow- 

 ing to a truncated point in front Iasis. 



/3, 1 One species zonaria. 



b, 4 Solitary form with a pair of well-developed postero-lateral appendages. 

 bb, 1 Atrial siphon in both solitary and aggregated forms tubular; body 

 muscles in both forms confined to the dorsal half of the body, 

 numerous in the solitary form, most of them interrupted both dor- 

 sally and laterally; body muscles 5 in aggregated zooid Ihlea. 



/3. / One species vagina. 



bb, 2 Atrial aperature in both solitary and aggregated forms a slit. . . Thalia. 



/3, 1 Appendages in solitary form about as long as body, body 



muscles nearly parallel, interrupted ventrally. Body 



muscles of aggregated zooid with from 5-11 fibers 



each longicauda 



