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UNITED STATES NATIONAL MUSEUM BULLETIN 251 



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Figure 47. — Distaplia cylindrica (Lesson) f. typica: a, proximal half of the 134 cm. colony, 

 sta. 106, b, outline of transverse section of colony; c, systems found in part of same 

 colony; d, right side of a zooid from same colony; e, ciliated groove. 



long tapers into a kind of peduncular portion where zooids are dis- 

 tributed only sparsely or are partly absent. 



Colony consists of a bundle of yellowish- white fascicular vessels 

 running along axis of colony and embedded in a somewhat loose, 

 soft, translucent, and milky whitish test matrix. These vessels issue 

 from the right posterior part of abdomens of respective zooids. Zooids 

 arranged in systems as shown in figure 47c, usually 8 to 17 in each 

 system, although zooids may reach 22-33 in larger elongated systems. 

 Zooids yellowish white in preservative, and attain 3 mm. in length 

 in contracted state. Abdomen about twice as long as contracted thorax. 



Branchial aperture 6-lobed, atrial aperture a huge opening with 

 a large languet. About 15 longitudinal muscles on each side of thorax, 

 several dorsal ones of these fairly fine; approximately one dozen 

 strong transverse muscles running beneath the longitudinal ones. 

 Stigmata in each of four rows about 15, parastigmatic vessels well 

 defined. Tentacles about 12, larger and smaller ones alternate rather 

 regularly. Ciliated groove (fig. 47e) a small oval opening. Dorsal 

 languets large and displaced to the left side from dorsomedian line. 



