14 MARINE POLYZOA. 



1. ALYSIDIUM PARASITICUM, n. sp. PL XIV. figs. 6, 7> 8, 9. 



Cells oval, narrow below ; a lateral process on either side above 

 and in front, on the sides of a depressed area, in which the aper- 

 ture is placed, and in which are two small perforations below the 

 aperture. Ovicelligerous cells, arising by a corneous tube from 

 the front of a cell. 



Hab. Algoa Bay, Port Natal, &c. 



A small delicate species, hitherto only observed parasitic upon 

 Carbasea armata ; but it appears to be very abundant. The ovi- 

 cells are very peculiar, and would afford an excellent subject for 

 examination in the living state. 



2. ALYSIDIUM LAFONTII. PL XIV. figs. I, 2, 3, 4. 



Cells much elongated and tubular below. Aperture superior, 

 margin with spines; a large avicularium in front immediately 

 below the aperture. Front of cell with numerous perforations ; 

 ovicell superior, cucullate. 



Eucratea Lafontii, Audouin, Expl. i. 242 ; Savig. Egypt, pi. 13. 



f. 2. 

 Hob. Coast of Spain, M' Andrew. Mediterranean? Savig. 



This species occurs abundantly on a piece of Eschara foliacea, 

 spreading across its hollows like a spider's web. In Savigny's 

 figure it is represented as growing upon a species of Fucus. It 

 is a very curious and remarkable form. 



3. CALPIDIUM. 



Cells with an avicularium on each side ; with two or more, 

 usually three, distinct apertures ; arising one from the upper part 

 of another in a linear series, all facing the same way and form- 

 ing dichotomously divided branches of an erect phytoid polyzoary : 

 cells at the bifurcation single. 



Calpidium, Busk, Voy. of Rattlesn. i. 364. 



This very peculiar genus is distinguishable from Catenicella in 

 the first place, by the anomalous circumstance that each cell is 

 furnished with two, or more usually with three, distinct keyhole- 

 shaped mouths, and is doubtless inhabited by three distinct 

 individuals. Whether these are separated from each other by 

 internal partitions is unknown, but the closest examination of 

 cells, rendered transparent by means of acid, fails to discover 

 such. In cells thus prepared there are apparent, however, three 

 distinct masses, reaching from the bottom of the cell to each 

 orifice, and which are probably the remains either of the body or 

 of the retractor muscles of the animals. 



