12 ALLAN HANCOCK ATLANTIC EXPEDITION REPORT 



ium. The opesia is variable in form, elliptical or oval to nearly round. The 

 operculum is moderately well chitinized, 0.10 mm in breadth. 



The peculiar vibracular chambers are more or less quadrate or rhom- 

 boid in form, alternate in position with the zooecia and vary greatly in 

 size, sometimes being nearly as large as the zooecia but usually only about 

 half as large. The opesia is distinctly auriculate, occupies one side of the 

 chamber and is tilted toward that side ; the lower edge is nearly straight 

 except for a minute denticle at the middle; the upper edge is more 

 rounded with a distinct lobe at its middle. The side of the chamber 

 opposite the opesia is elevated, rounded and bullate, smooth and shining 

 or slightly roughened in advanced calcification. The mandible has a 

 very short, small triangular base and a very long (as much as 0.80 mm) 

 brownish-yellow filament which is provided on one side with a continuous 

 row of short, fine, distally-projecting setae. 



The ooecium is endozooecial, very short, transverse, smooth and 

 slightly raised, appearing as a slightly bulging distal end of the zooecium. 



The measurements vary remarkably: zooecial length 0.25 to 0.40 

 mm, width 0.20 to 0.28 mm; opesial length 0.20 to 0.33 mm, width 

 about 0.19 mm; the vibracularian chamber averages 0.18 mm in length 

 but may be much larger, its opesia averages 0.12 mm in length and 

 0.06 mm in width. 



The zooecial characters conform rather closely to those of F. laxi- 

 basis Canu and Bassler (1928:23) from the Pliocene of Bocas Island, 

 Panama, but the measurements are somewhat different and there are 

 other minor characters. It is probably better to keep the recent form 

 separate from that of the Plioecene. The two species V. viator and V. 

 crassatina described by Canu and Bassler (1929:97, 98) from the 

 Philippines are larger than caribbea and differ in some other respects. 



It is a fortunate circumstance that 3 of the more than 200 colonies 

 were living and show the chitinous structures, which hitherto have not 

 been described in this genus. This is the first record of the genus living 

 in Atlantic waters. 



Type.—AYiY no. 1. 



Type locality. — Station At503, 1 mile SW of Cape la Vela, 

 Colombia, 10 fms, very numerous. 



Distribution.—Stztlom A14-39, A42-39, At505, At525, At526, 

 At528, At529, and At530. These stations place the locations at Cape la 

 Vela, Colombia; Margarita, Aruba, and Tortuga Islands, and the Gulf 

 of Venezuela at 19 to 41 fms. 



