52 UNITED STATES NATIONAL MUSEUM BULLETIN 251 



shaped protuberances along the margin (fig. 155) ; the margin of these 

 fine protuberances is sprinkled with dark pigment. 



Test soft, gelatinous, translucent, milky white, brownish or dark 

 brownish ; the coloration varies according to amount of pigment cells ; 

 no sand grains embedded in test. Zooids, yellowish orange, brown or 

 grayish brown, are seen through the test. Zooids rather small, thorax 

 1.7 mm.-2 mm. in length in somewhat contracted state. Abdomen 

 usually one-half to two-thirds the length of thorax, but may be as long 

 as thorax in some zooids. Postabdomen usually smaller than abdo- 

 men, approximately half the length of abdomen, although in a fully 

 mature state it reaches the length of abdomen. In the small colony 

 from Saipan Island, 8 mm. X 4.5 mm. in extent and 4.5 mm. in thick- 

 ness, some zooids are provided with an elongated postabdomen which 

 may be as long as thorax (compare fig. 15/ with fig. 15^7) ; these long 

 postabdomens are filled with mesenchyme cells, but contain no mature 

 gonads. Probably this feature is due to an unusual overgrowth. 

 Branchial aperture 6-lobed, atrial aperture situated at level of first to 

 third transverse vessel. Atrial languet long, but exact length and 

 shape of tip are unknown, as no zooids could be taken from the test 

 perfectly with the atrial languet whole. Small prominence found on 

 the dorsomedian line just posterior to atrial aperture. Six strong 

 longitudinal muscles on each side of thorax, also a few delicate ones on 

 dorsal side. Extremely delicate fibrous structures running trans- 

 versely or obliquely between endostyle and atrial aperture faintly 

 discernible on some zooids, but it is not yet ascertained whether the 

 structure is truly muscular or not. Stigmatal rows usually 12-13, 

 ranging from 10 (Pliilippine specimens) to 15 (specimen from Oahu 

 Island) ; 12-20 stigmata in each row. Papillae on horizontal mem- 

 branes along transverse vessels, arranged roughly one for each stigma ; 

 in some zooids tip of papillae sometimes colored by aggregated whitish 

 corpuscles. Tentacles 12-22 in zooids examined, including larger and 

 smaller ones, sometimes marked by whitish pigment spots. Ciliated 

 groove a small elliptical opening. Dorsal languets not large, situated 

 approximately on dorsomedian line or slightly displaced from median 

 line to the left for the distance of about two stigmata. Anus bilobed, 

 opening at the level of the seventh transverse vessel (exceptionally at 

 the sixth transverse vessel). Four to five embryos, mature and im- 

 mature, found in zooids of the colonies from Oahu Island. Intestinal 

 loop twisted as usual in species of the genus Polyclinum. Distal por- 

 tion containing pericardium rather small, scarcely reaching half the 

 length of postabdomen. Ovary is centered; testicular follicles 3-11 

 in specimens from Saipan Island, but 12-39 in specimens from the 

 Hawaiian Islands. 



Larv^ae elliptical in shape, 420-580/i in length. Test somewhat 

 frothy in younger stages, but somewhat granulated in grownup stages. 



