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UNITED STATES NATIONAL MUSEUM BULLETIN 251 



Figure 70. — Polycarpa captiosa (Sluiter): a, Left half of mantle body of 25 mm. individual 

 from Saipan, inside; b, right half of same; c, ciliated groove of same specimen; d, left 

 half of mantle body of the 8 mm. long specimen from Saipan, inside; e, ciliated groove 

 of same. 



Island were examined. The smallest (8 mm. long) individual roughly 

 oval in outline, while other larger ones are all elongated. Branchial 

 aperture subterminal; atrial aperture situated near middle in larger 

 specimens, slightly posterior to middle of body in others ; both aper- 

 tures 4-lobed. Test leathery and tough, yellowish white in smaller 

 Saipan specimens, but grayish red in larger Palau specimens. In 

 smaller specimens, mantle yellowish white, very thin, delicate, adher- 

 ing firmly to test and provided very sparsely with longitudinal muscles 

 converging to apertures. Fine tentacles on atrial velum and endocarps 

 on inner surface of mantle. Inner longitudinal vessels of branchial 

 sac in smaller specimens are arranged (D= dorsal, V= ventral) : 



