223 



the coenenchyma form externally a layer of scales which exhibit more or 

 less irregular or dentate margins, one or more, longer or shorter, warty pro- 

 cesses being given off from each centre. Beneath this there is a layer of warty 

 irregular spindles, including tri- or hex-radiate forms. Spicules of the same 

 shapes are found in the polyp calyces. 



Several species have from time to time been established so that the follow- 

 ing are now recognised : B. ino/lis, Philippi ; B. studarl, Whitelegge ; B. 

 pliilippi Studer ; B. //icksoni, Thomson and Henderson; B. indica, Thomson; 

 and to these we add in this memoir, B. tenuis, n. sp. 



There are also in this collection several colonies which we had great 

 difficulty in relegating to any well-defined species but which seem to link to- 

 gether B. iiutllh, B. stuih'ri and B. j^liiUppi. The following sununaries of these 

 three species will show what the alleged specific differences are. 



B. mollis, Philippi. 



The branching is irregular, the verrucae are almost or quite as high as 

 broad ; the oral [)ortion of the polyps bears spicules. The spicules of the 

 coenenchyma are in two layers, as also in the verrucas. The colour is brownish, 

 the polyps are translucent white ; the branches and twigs are almost uniform in 

 thickness. Anastomosis is common. The axis is light brown, rather delicate 

 and flexible. Spicules : The outer layer consists of closely packed, short, 

 conical bodies with their main axis perpendicular to the surface ; the broader 

 end is usually turned outwards and bears long finger-shaped processes often 

 united in little groups ; the middle portion is smooth and conical ; the inner 

 end bears four to six strong ])rocesses which again bear small secondary warts 

 often divided at the ends. These spicules often show a marked middle line 

 along their main axis. The spicules of the inner layer are of very different 

 forms, but are deducible from the preceding more or less irregular spindles. 

 On the extended polyp the basal part is free from sjDicules, but around the bases 

 of the tentacles there is a well-defined ring consisting of })ointed spindles ; 

 nearer the mouth on the base of each tentacle there is a triangular arrangement 

 of three to four larger needles with strong warts. Between the tentacles there 

 is usually a Hat single needle ; on the aboral surface of the tentacles there is a 

 double row of small .spicules. 



Localities: Naples, Messina, Syracuse, "Mare Scoticum" (see Carus, 

 "Prod. Faunte Medit.," p. 60). 



B.pkili2>2n, Studev," ' Chsdlengev'liiepovt," vol. xxxii. p. 10. Plate III. figs. 



3a, 3b ; Plate V. fig. 7. 



"The spicules of the coenenchyma and of the calyces form as in B. mollis 

 two layers ; the upper of these shows the characteristic form described by 

 Kolliker and figured by von Koch. I observed, as the essential form, more or 



