KEY TO SPECIES OF CEPHALODISCUS. 11 



Tubarium. Colony massive, maximum size of known specimens 190 by 115 mm., 

 with twelve branches (plate 1) ; maximum width of a single branch 32 mm. 

 Branches roughly cylindrical, with narrowing extremities. Peristomes tubular at 

 the extremity of the branch, and occasionally elsewhere. The abaxial edge 

 produced into a blunt lip ; no conspicuous ridge continued down from the 

 extremity of the lip. Width of lumen of tube 1*2 to 1'3 mm. (fig. 10, plate 4). 

 Polypides large, 4 5 mm. from front of buccal shield to end of visceral mass ; 

 surface deeply pigmented, so as to appear black to the naked eye. Males, females, 

 and hermaphrodites (one ovary and one testis) not distinguishable externally. 

 Plumes usually seven pairs, axes massive, black, no end bulbs with refractive beads. 

 Stolon short, stout, and transversely wrinkled in contracted state, usually directed 

 posteriorly ; buds from 2 to 9, some upon secondary stolon where the number is 

 large. Free ova 6 mm. across. 



Species levinseni. Material. One specimen, belonging to the Copenhagen 

 Museum, obtained off the West coast of Japan, at South end of the Corea Strait, 

 in 100 fathoms. Described by Harmer in the Eeport of the ' Siboga' Expedition 

 (10). Tubarium subcylindrical, slightly branched, reaching a length of at least 

 132 mm. Ostia at ends of distinct tubular peristomes, which radiate in all 

 directions, at an angle greater than a right-angle, from the principal axis of the 

 branch, each being produced on its abaxial side into a single, short, blunt process 

 or lip (text-fig. 3). Width of branch (from tip to tip of peristomial lips) 12 mm. ; 

 width not including peristomial tubes 3 to 5 mm. ; width of cavity of tube about 



7 mm. ; a ridge present on the outer (abaxial) surface of the peristomial tube, 

 terminating in the end of the lip. Polypides colourless ; all known individuals 

 are female ; body cylindrical, front of buccal shield to end of visceral mass 1 5 mm. 

 or more ; stalk of buccal shield exceptionally long. Plumes six pairs, without end 

 bulbs or refractive beads. Stolon thick, about as long as the rest of the polypide, 

 usually directed posteriorly, producing buds in small numbers. Free ova 3 to 



4 mm. across. 



KEY TO THE IDENTIFICATION OF THE SPECIES OF 



CEP HA L ODIS C US. 



Polypides in a common cavity with numerous ostia (sub-genus Demiothecia). 



Width of branches, 2 mm. or less ; colony diminutive ; plumes, less than six pairs. 



Polypides, black ; plumes, four pairs, except in males, which have one pair only . sibogae. 

 Polypides with black pigment on stolon only ; plumes, five pairs . . . gracilis. 

 Width of branches, 4 mm. or more ; plumes, six pairs. 



Cavity of tubarium with smooth inner .surface ; distance from one branch to 



the next about 10 mm hodgsoni. 



Cavity of tubarium incompletely subdivided by ridges and partitions of irregular 

 shape ; distance from one branch to the next about 22 mm. . . . dodecalophus. 



