22 UNITED STATES NATIONAL MUSEUM BULLETIN 251 



Since it would have been difficiiU. to insert in the present paper all the 

 synonyms and supplementary notes in tliose papers concerning the 

 species here treated, only the most significant liave been noted herein. 



ASCIDIACEA 



Order Aplousobranchia : Family Synoicidae 



1. Aplidium lobatum Savigny 



Figures la-f 



Aplidium lobutiim Savigny, 1816, p. 182, pi. 3, fig. 4, pi. IG, fig. 1. — Van Name, 

 1921, p. 203, fig. 3.— Van Name, 1930, p. 425, fig. 4.— Van Name, 1945, p. 28, 

 fig. 3.— Tokioka, 1955, p. 43, pi. 1, figs. 1-5. 



Aplidium iremulum Savigny, 1816, p. 184, pi. 16, fig. 2.— Sluiter, 1909, p. 99. 



MATERIAL EXAMINED 



Marianas Islands, Saipan : P. E. Cloud, sta. D-8. One colony, 9 mm. X 5 

 mm. in extent and 2.5 mm. in thickness. White sand grains densely cover the 

 surface of the colony and also impregnate the test. The zooids are preserved 

 very poorly (USNM 11471) . 



Palau Islands, Iwayama Bay : GVF sta. 30. Two small colonies, 6 mm. X 5 

 mm. and 7 mm. X 4 mm. in extent and up to 2.5 mm. in thickness. They are 

 attached to algae and contain minute sand grains embedded in the test. The 

 zooids are strongly contracted (USNM 11459). 



Gilbert Islands, Onotoa Atoll : P. E. Cloud, sta. GOC-59. A small colony, 

 6 mm. X 2 mm. in extent, attached to a colony of Didemtmm {Didemnum) 

 candid um (Savigny), and densely covered vi'ith sand grains over its surface; 

 sand grains also impregnate the test densely throughout, from the surface to 

 the interior. The colony is considerably mutilated and the zooids are also 

 preserved somewhat poorly (USNM 11514) . 



Description. — Test soft, transparent or translucent, quite color- 

 less or faintly yellowish brown. Due to imperfect state of preserva- 

 tion system of zooid arrangement is hardly observable on surface; 

 only a single central common cloacal aperture can be seen on the 

 specimen from Saipan, and on one of the specimens from the Palau 

 Islands. Common cloacal aperture about 2 mm. in diameter, margin 

 fringed with 14 finger-shaped lobules on the Saipan specimen (fig. 

 Id). Zooids about 1 mm. in length, in a strongly contracted state 

 (fig. la). In contracted condition, thorax about 1.5 times length of 

 abdomen; branchial aperture 6-lobed, tip of atrial languet simple or 

 trifid; G to 10 strong longitudinal muscles on eacli side of thorax; 

 6 to 9 stigmatal rows. Stomach situated nearly at middle of abdo- 

 men, with 5 longitudinal plications including typhlosole. Proximal 

 end of rectum constricted distinctly from the foregoing part of alimen- 

 tary canal, may show a pair of slightly swollen caeca in those zooids 

 in better condition. About 3 stigmatal rows posterior to level of 

 anus. Gonads not found in any of the zooids examined. 



