NEW SPECIES OF MYOSOMA 175 



lophophore obliquely placed. Calyx devoid of spines. Tentacles number- 

 ing 14. Dioecious. 



Description: The zoaria form prominent tangled masses, making the 

 determination of the path of an individual stolon rather difficult. The 

 stolons ramify, criss-cross to form a mat upon the substratum. In the 

 present specimens, the stolons rested upon the stems of trophosomes of 

 the hydroid Bougainvillia sp? There are non-polypide bearing or sterile 

 stolonal segments occurring with no apparent order or regularity. 



The reptant segmented stolons give rise to erect, well chitinized poly- 

 pides consisting of two distinct anatomical regions, the pedicel and the 

 calyx. The pedicel is muscular, possessing muscle fibers that are placed 

 diagonally as well as muscle fibers that parallel the long axis of the 

 pedicel. The chitinous cuticle, in preserved specimens, shows many fine 

 transverse wrinkles or annulations. Miss Robertson described a heavy 

 ventral muscle band traversing the length of the pedicel and continuing 

 into the calyx. As mentioned above, the present study does not confirm 

 this observation in either Myosoma spinosa Robertson or Myosoma han- 

 cocki. The pedicels of Myosoma hancocki are completely lacking in spines. 

 In sexually mature individuals, the length of the pedicel ranges from 

 515 ja to 745 /A, well short of the length attained by Myosoma spinosa. 



The calyx has an obliquely situated lophophore with its crown of 

 ciliated tentacles. The anatomical pattern is typically entoproctan, hav- 

 ing a "U" shaped alimentary tract with both the oral and the anal aper- 

 tures opening into the lophophore. Also within the caljTC are found the 

 reproductive organs, the nephridia and the nerve ganglion with its sensory 

 fibers. 



Myosoma hancocki is dioecious, the reproductive organs are paired 

 and laterally placed. The male and female individuals occur together 

 within the same zoarium and along the same stolon. The calyx in sexu- 

 ally mature individuals ranges in size from 250 ju, to 345 /x in length and 

 from 180 /i to 230 ,a in width, being notably sm.aller than the calyces of 

 Myosoma spinosa. An examination of a large number of polypides failed 

 to reveal a single calyx possessing spines. 



Holotype: AHF number 135. 



Repository: Allan Hancock Foundation, The University of Southern 

 California, Los Angeles, California. 



Type locality : Malabon, Rizal Province, on fish pond gates of the Dagat- 

 dagatan Saltwater Experimental Station, March, 1954, collector, Jose 

 S. Domantay. 



