78 UNITED STATES NATIONAL MUSEUM BULLETIN 251 



dum-typQ in the present species and somewhat smaller than in Lis- 

 soclinwn j)ulvinuin^ and the consistency of the test seems more fragile 

 in D. tematanum than in L. qmlvinum. 



28. Didemnum ( Polysyncraton) sagamiana Tokloka 



FiGUBES 25a, ft 

 Didemnum (Polysyncraton) sagamiana Tokloka, 1953a, p. 196, pi. 21, figs. 1-3. 



MATERIAL EXAMINED 



Palau Islands : USNM Accession 206221, sta. 25-865, three colonies. 



Description. — Of the three colonies examined the largest is 5 

 mm. X 3 mm. in extent and 1 mm. in thickness. Faintly grayish white, 

 darker in nuance where zooids are embedded. Spicules distributed 

 densely and evenly throughout test, superficial spiculeless layer dis- 

 tinct, although not remarkable. Spicules rather small, 16-32jU, in 

 diameter and 22/a on an average, candidum-type,; rays numerous, 

 very short and bluntly tipped. 



Zooids rather large; abdomen about 620/u, in length. Branchial 

 aperture 6-lobed, atrial aperture wide and with bifid atrial languet; 

 retractile muscle distinct. Testicular follicles 5-7 in zooids examined ; 

 proximal part of vas deferens coils II/2 to 2i/^ times. Intestinal loop 

 not curved as sharply as in subgenus Diderrinmn. 



Larval test frothy ; two pigment flecks of sensory organ arranged 

 anteroposteriorly. Number of ampullae cannot be given clearly, as all 

 examined embryos were not fully developed. 



29. Didemnum (Polysyncraton) semifuscum (Sluiter) 



Figures 25c-/ 

 Didemnum semifuscum Sluiter, 1909, p. 62, pi. 3, figs. 28-30. 



MATERIAL EXAMINED 

 Gilbert Islands: Collected August 25, 1951; 11 small colonies (USNM 11486, 

 11490). 



Description. — Eleven small whitish colonies from the Gilbert 

 Islands were examined, tlie largest is 6 mm. X 4 mm. in extent and 1 

 mm. in thiclmess. A single common cloacal aperture located near the 

 center of respective colonies and fringed with 5 or G lobules, as shown 

 in figure 25(7, Spicules 31-47/x in diameter, 39fi on an average, candi- 

 dum-type (fig. 25<Z) consisting of many sliort, acutely pointed rays, or 

 nearly spherical in shape with a number of small conical prominences 

 on surface (fig. 25e), which are 15-20 (about 18 on an average) on the 

 equatorial plane. Spicules distributed very densely and evenly 

 throughout test from surface to bottom. Zooids stained dark grayish ; 



