REPORT ON THE ALCYONARIA. xvii 



spicules of the mesoderm. At short intervals the tubes are united by calcified transverse 

 lamellae formed from the stolons in which the polyps originate. The anterior portirm of 

 the i^olyps is retractile. 



Tubipora, Linne, Syst. Nat. ed. 10, t. i. p. 789 ; Lamarck, Hist. Nat. Anim. sans Vert., 

 t. ii. p. 207, and ed. 2, p. 324 ; Lamouroux, Expos, meth. des Polyp, p. 6G; 

 Blainville, Manual d'Actinologie, p. 500 ; Ehrenberg, Corall. des rothen 

 Meeres, p. 55; Perc. Wright, Ann. and Mag. Nat. Hist, 1869, ser. 3, 

 pp. 377-383 ; G. v. Koch, Anatomic d. Orgelkoralle, Jena, 1874 ; Klunzinger, 

 Korall. des rothen Meeres, 1877, pt. i. p. 46; Sidney F. Hickson, Quart. 

 Journ. Micr. Sci., 1883, xcii. pp. 516-528. 



Family IV. X e N 1 1 d .e. 



Xenidse, Verrill, Proc. Essex Inst., vol. iv. No. 5, 1865, p. 148. 



Xeniadx, Gray {pars), Ann. and Mag. Nat. Hist., 18-59, ser. .3, vol. iv. p 443. 



The colony consists of masses of long cylindrical polyps, which Ijear terminal crowns 

 of non-retractile tentacles. The polyps are in their lower portion united by coenenchyma 

 in which are the ramifications of the canalicular .system uniting the individual polyps. 

 This coenenchjTna sometimes forms a branching axis, from the upper .surface of which the 

 free portions of the polyps project. The spicules are feebly calcareous disks. 



Xenia, Savigny, Lamarck, Hist. Nat. Anim. .sans Vert., t. ii. p. 409, 1816, ed. 2, 

 p. 625 ; Lamouroux, Expos, method, d. polyp, p. 69 ; Klunzinger, Korall. des 

 rothen Meeres, pt. i. 1877, p. 39. 



Heteroxenm, Kolliker, Festschr. d. 25 Jahrg. phys.-med. Ges. Wiirzburf,', 1875, p. 12. 

 Comularia (j/ors), Quoy and Gaimard, Voy. Astrolabe, t. iv. p. 265, Zooph., pi. 22, fig, 1. 

 Cespitularia. Valenciennes, in Paris Museum. 



Xenia seems closely allied to Anthelia, exhibiting in the prolongation of the polyp- 

 tubes, and in the marked development of the coenenchyma an advance in the colonial 

 system. Heteromorphic forms were first observed by Kolliker in a new species, for 

 which he instituted the genus Heteroxenia. 



Klunzinger finds bud-like polyps in Xenia umhellata. and Xenia fvscesceas, Ehrbg.; 

 in the former .species, where they appear sparingly or are wanting, he leaves it an open 

 C[uestion whether they are zooids or buds ; in the last species he inclines to the opinion 

 that they are zooids which do not develop beyond the bud-like stage. In a paper by 

 W. Haacke (Zur Physiologic der Anthozoen, Zool. Gart. xxvii.), thef author maintains, on 

 the strength of his ob.servatiou of the living animals, that the supposed zooids are buds 

 which develop later into polyps. These observations, which appear to us trustworthy. 



