498 ALCYONIDIIDxE. 



series ; on each side runs a margin of tlic gelatinous (?) 

 crust. The series bifurcate frequently, two lines origi- 

 nating from the summit of a cell. At the bifurcation the 

 crust forms a web-like expansion between the two series. 

 Every here and there collections of cells occur, from which 

 the single series are given off. 



I have only had the opportunity of examining dried 

 specimens of this form ; and there is therefore a possibility 

 that in some points the characters may not be ade- 

 quately represented. 



Alcyonidium mytili, Dalyell, 

 Plate LXX. figs. 2, 3. 



Alcyonidium mytili, Daly. Rem. An. ii. 36, pi. xi. : Smitf, loc. cit. 490 & 



507, pi. xii. figs. 1, 2. 

 Alcyonidium iiexagonum, Hinchs, Quart. Journ. Micr. So. t. 176; Ann. 



N. H. ser. 3, ix. 470 : Alder, North. Cat., Trans. Tynes. P. C. 



1857, 65 (sep.). 

 Alcyonidium parasiticum, Smitt, Qifv. Vet.-Ak. Forh. 1865, 27, j)l. v. 



figs. 8-19. 

 PSarcociiitum polyoum, Gosse, Mar. Zool. 



Zoarium incrusting, fleshy, dingy white or yellowish, some- 

 times of a darker colour; thickly covered, when the 

 polypides are retracted, with very small obtuse promi- 

 nences. Zocecia hexagonal, the septa showing distinctly 

 on the surface. 



Ovarian cells scattered over the zoarium, the ova opaque- 

 white, disposed circularly within them. 



Polyjnde with about 15-18 tentacles. 



Habitat. On shells, stones, and Fucus from tide-marks to 

 deep water. 



Localities. Probably very common and generally dis- 

 tributed, though few localities have been recorded. Scot- 



