REPORT ON THE ALCYONARIA. Ixi 



colony, which is ramified in one plane. The horny axes are frequently flattened in the 

 same plane, and the coenenchyma is also compressed. Thus the stem and branches 

 show in section two flattened surfaces and two edges. The polyps are ranged chiefly 

 on the edges of the axis, and, in some cases, they occupy it alone, but in rare cases 

 they are found massed on the flattened surfaces (Hymenogorgia). The system of 

 longitudinal canals shows the same tendency. The longitudinal canals vary in width 

 according to their position on the axis. Through the lateral position of the polyps, 

 the longitudinal canals, which run along the surface of the axis, are very few in 

 number, as in the smaller species of Lej^togorgia, in which, — as, for example, in 

 Leptogorgia arbuscida, Verr. — only one large longitudinal canal runs along the 

 flattened side of the axis. The course of the larger longitudinal canals is often 

 indicated externally bj one or more ridges or furrows on the ccenenchyma. In some 

 cases the larger longitudinal canals run along the edges of the compressed axes, while 

 smaller ones course down their flattened surfaces. This is the case in Gorgonia 

 anceps, Pall., for which, therefore, the generic name Xijihigorgid, Milne-Edwards, is 

 retained. Swiftia, DucLassaing and^ Michelotti, appears to belong to the GorgonidiB, 

 though in their Memoir on the Corals of the Antilles these authors place it among the 

 Primnoidse. 



1. Platycaulos, n. gei. 



2. Lophogorgia, Milne-Edwards. 



3. Leptogorgia, Milne-Edwards, emend. 



Verrill. 



4. Stenogorgia, Verrill. 



5. CalUstephanus, n. gen. 



6. »S«yi/'Z«a,Duchassaingand Michelotti. 



7. Gorgonia, Linneus, emend. 



Verrill. 



8. Eugorgia, Verrill. 



9. Danielssenia, Grieg. 



10. Xiphigorgia, Milne-Edwards. 



11. Hymenogorgia, Valenciennes. 



12. Phycogorgia, Valenciennes. 



1. Platycaulos, n. gen. 



The colony is branched in one plane, the branches sometimes anastomosing. The axis 

 is horny, compressed, with a calcareous centre and calcareous particles interspersed. The 

 nutrient canals are symmetrical. Polyps prominent on edges of the stem and branches, 

 retractile within verrucse. The ccenenchyma is moderate, tough, the spicules, straight 

 and curved, spiny spindles and stellate forms. 



2. Lop)hogorgia, Milne-Edwards, Hist. Nat. des Coralliaires, t. i. p. 167. 



Gorgonia, Kolliker (pars), Icones histiologicae, pt. ii. p. 1 39. 



Leptogorgia, Verrill (pars), Amer. Journ. Sci. and Arts, vol. xlviii. p. 425. 



The colony is upright, branched in one plane, with flattened stem and branches; the 

 terminal twigs assume a cylindrical form. The polyps are sunk into the coenenchyma 

 without forming true verrucse. 



(ZOOL. CHAI.L. EXP. — PART LXIV. — 1889.) SsS I 



