PACIFIC TUNICATA OF U.S. NATIONAL MUSEUM 35 



Desckiition, — Four ol' the six colonies are represented by a single 

 cormidium eacli, wliile each of the otlier two consists of two cormidia 

 attached to each other side by side at their basal portions. Largest 

 cormidium .3.5 mm. in diameter and 4 mm. in length. Distal half of 

 each cormidium occupied by thoraces of zooids; upper half of the rest 

 of the colony contains abdomens. From 5 to 12 (average about 8) 

 zooids, usually yellowish in color, arranged around a central, plainly 

 margined common cloacal aperture, with their darkly colored endo- 

 styles toAvard the periphery of the colony. Several whitish fecal pel- 

 lets found in cloacal lacuna just under common aperture. A parasitic 

 copepod was found in the basal portion of one of the colonies. 



Test gelatinous, translucent, densely sprinkled with many minute 

 grayish- violet pigment spots. Surface quite free of foreign material. 

 Zooids up to 4 mm. in length, embedded perpendicularly in test. 

 Thorax and abdomen nearly equal in length, postabdomen short, less 

 than two-thirds of abdomen. No constriction between abdomen and 

 postabdomen. Branchial aperture 6-lobed, atrial languet rather short 

 and trifid, darkly pigmented at tip. About 15 longitudinal muscles 

 on each side of thorax, several ventral muscles running rather 

 obliquely. Stigmatal rows 6, 15-18 stigmata in each row. No papillae 

 along transverse vessels. Tentacles about 6. Ciliated groove a small 

 oval opening. Dorsal languets roughly triangular and slightly dis- 

 placed to left side of dorsomedian line. Peripharyngeal band heavily 

 pigmented. Anus bilobed, opening at level of fourth transverse vessel. 

 Stomach roughly globular in shape and situated near middle of 

 abdomen, with about 30 longitudinal plications on its surface. Dis- 

 tinct caeca formed at proximal end of rectum. No gonads found in 

 postabdomen of zooids examined. 



Remarks. — The present specimens veiy closely resemble A. mono- 

 tonicum Tokioka from the Tokara Islands near Okinawa, but differ 

 in the coloration of the colony (grayish violet instead of reddish 

 orange in the latter), the number of longitudinal plications on the 

 stomach surface (nearly twice the number in typical A. monotonlcum) 

 and in the appearance of the proximal end of the rectum (caeca are 

 indistinct in the latter). It is very difficult to judge wdiether or not 

 these differences should be regarded as significant characteristics dif- 

 ferentiating the present specimens from the tyi:)ical A. 7nonotonicum. 

 Thus, at present, the specimens are described here provisionally as a 

 form near A. rnonotonlcuin. 



9. Aniarouciuni mulliplicatuni (Sluitcr) 



Figures 8, 9 



ApVulium mtiltiplicatum Sluitcr, 1909, p. 101, pi. 5, fig. 5. 



Amaroucium multiplicatum Van Name, 1918, p. 105, lig. 113; pi. 31. fig. 20. 

 Amaroucium sp. aff. multiplicatum Tokioka, 1953a, p. ISl, pi. 10, figs. 1-4. 

 f Amaroucium californicum Hitter and Forsyth, 1917, p. 483, pi. 4G, fig. 72. 



