48 



UNITED STATES NATIONAL MUSEUM BULLETIN 251 



System of zooid arrangement usually obscure due to strong contrac- 

 tion of zooids, although some systems could be discerned rather clearly 

 in dissected colonies. Abdomen about half the length of thorax; 

 postabdomen approximately two-thirds the abdomen length. Bran- 

 chial aperture 6-lobed, atrial aperture situated near anterodorsal 

 corner of thorax. Tip of atrial languet denticulated with 8 to 10 



Figure 14. — PolycUnum tsutsuii Tokioka: a, the smallest colony from the Gilbert Islands; 

 b, postabdomen of zooid of the 17 mm. X 5 mm. colony from the Gilbert Islands; c, 

 postabdomen of zooid of the colony in figure a; d, tip of atrial languet of the zooid shown 

 in figure b; e, 10 mm. X 7 mm. colony from the Palau Islands;/, abdomen and postabdomen 

 of a zooid of same colony (v.d. = vas deferens); g, embryo from same colony; h, right 

 side of a zooid of the colony from the Philippine Islands; i, tip of atrial languet of same; 

 ', small prominence just behind atrial aperture of same; k, ciliated groove of same. 



