PACIFIC TUNICATA OF U.S. NATIONAL MUSEUM 



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Figure 4. — Aplidium yezoense, new species: a, one of the colonies; b, zooid with minute 

 thorax; c, intestinal loop; d, section of stomach. 



several zooids. Distal portion of cormidium where thoraces of zooids 

 are embedded somewhat soft in consistency as compared with basal 

 half. Zooids may reach about 9 mm. in length. Thorax missing in 

 most zooids or very small when it exists. Colonies probably in resting 

 stage when all old thoraces are torn down and new ones are in process 

 of regeneration. Eight stigmatal rows ? Both abdomen and postab- 

 domen filled compactly with mesenchyme cells; postabdomen much 

 longer than abdomen. Intestinal loop may reach 4 mm. in length. 

 Stomach considerably wider than long with 4 longitudinal plications 

 on surface, situated at level of posterior one-third of length of intes- 

 tinal loop. Hind stomach distinct; middle intestine occupies pos- 

 terior end of intestinal loop and is marked with a few irregular longi- 

 tudinal folds. Proximal portion of rectum swollen distinctly at level 

 of posterior margin of stomach forming a pair of roundish caeca. 

 Gonads not found in zooids examined. 



Remarks. — In Amaroucium fragile Redikorzev, 1927, from the 

 Okhotsk Sea, the colony consists of many cormidia, the zooids are 

 provided with 10-11 stigmatal rows and the stomach with 4-5 longitu- 

 dinal plications. These features somewhat resemble those of the 



