118 Transactions of the Sociefj/. 



pared to the disk of a Composite's capitulum and the periphera 

 parts to the ray-florets (plate XVI. fig. 1). 



There are large longitudinal canals in the central dome, 

 separated by tough hyaline mesoglcea. Very strong muscle-bands 

 pass down their walls, and there are others in the wall of the cup 

 reaching almost to the margin. These longitudinal hands pass for 

 a short distance into the wisp-like stalk and gradually disappear. 

 Numerous well-defined transverse muscles extend l)etweeu the 

 several longitudinal bands. 



Tfie Clip.— The cortical part of the wall of the cup, which is 

 very definite and has a thickness of about 2 mm., is extremely 

 hard, consisting mainly of long spindle.s, readily visible to the 

 naked eye (some over o mm. in length), arranged for the most 

 part in longitudinal interlacing rows. On the surface many of the 

 spindles lie exposed throughout their whole length. Towards the 

 base of the cup the spicules increase in size, and they attain their 

 maximum dimensions — almost 1 cm. in length — in the basal wisp. 

 These are probably the largest Alcyonarian spicules as yet 

 kno%vn. 



The internal part of the wall of the cup, as distinguished from 

 the hard cortex just described, is soft and muscular. It is about 

 9 mm. in thickness where it joins the base of the dome, and naiTows 

 gradually to the margin of the cup. 



TJie System of Canals. — Each of the finger-like polyp-bearing 

 lobes has a large canal, with which the cavities of the polyps 

 communicate. These branch canals pass into the dome or the 

 wall of the cup, as the case may be, and uniting with others 

 form the main longitudinal canals. These are relatively large, 

 especially at the base of the cup and below the central dome, where 

 they are about 2 • .5 mm. in diameter. From this region of maximum 

 size, they gi-adually taper into the wisp-Kke stalk. The walls of 

 the canals bear the strong longitudinal muscle-bands, and there 

 are verj' few spicules. 



Polyp-bearing Lobes or Branches. — Looking down into the 

 mouth of the cup, one sees the heads of between sixty and seventy 

 polyp-bearing lobes or branches, Init the number visible will of 

 course depend on the degree to which the dome is contracted. 

 Besides the branches on its summit, the central dome bears four 

 whorls, and there are also four tiers on the wall of the cup. It 

 should be noted, however, that the lobes do not all arise singly 

 from the central dome, but may cohere for a distance of 2-6 mm. at 

 their bases. Some are united in pairs ; in one case seven were 

 found to be cohering. 



Polyps. — Each of the finger-like branches resembles a spike- 

 inflorescence, and bears 1.50-200 close-set sessile polyps. These 

 almost cover the surface, but without discernible arrangement. At 



