PACIFIC TUNICATA OF U.S. NATIONAL MUSEUM 



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Figure 73. — Polycarpa psammotesta Tokioka: a, right half of mantle body of 33 mm. 

 specimen, inside; b, left half of same; c, intestinal loop of 30 mm. specimen from Hako- 

 date, side of attachment; d, e, ciliated grooves;/, large gonad, side of attachment. 



Descrittion. — Five specimens from Japanese waters were examined. 

 They are ovoid in shape, 22 mm.-35 mm. in length, densely encrusted 

 with fine sand grains all over the surface, just as in many forms of 

 Molgulidae. In fact, it was practically impossible to distmguish this 

 species from Molgula {Molgula) xenophora Oka without dissecting 

 them — these two forms were found together in the same collection. 

 Both apertures quite invisible on surface, although marked distinctly 

 on inner surface of test, distance between them is 33-43 percent of body 

 length. In some specimens sand grains encrusting dorsal side of test 

 were finer than those encrusting ventral side. 



Test thin, about 1 mm. in thickness, impregnated with sand, very 

 fragile. Mantle yellowish or yellowish brown, very delicate ; muscula- 

 ture feeble. Branchial aperture subterminal and atrial aperture sit- 

 uated near middle of body; both siphons insignificant. Small endo- 

 carps present along ventral branch of intestinal loop. Fine tentacles 

 along margin of atrial velmn. In branchial sac inner longitudinal 



