292 HISTORY OF BRITISH ZOOPHYTES. 



the extremities ; aperture lateral, near the distal end. Polypes 

 Ascidian. Johnston. 



1. HIPPOTHOA CATENULARIA, Professor Jameson. (Plate 

 XV. fig. 54.) 



Hab. On shells, especially bivalves, from deep water. 



This is a very handsome little coralline. Dr. Johnston 

 very properly describes it as "formed of a series of cells 

 connected like a string of bugles ; cells oval, widest and 

 rounded anteally ; its aperture oval, with a plain thickish 

 rim placed near the top/' Mr. Gray states, that when 

 alive "it appears like dew-drops, and is easily separated 

 from the shell by a pin, but is strongly attached when dry." 

 We have observed this, and also what Dr. Johnston men- 

 tions, that in this state (when dry we suppose) the aperture 

 of the cells is sometimes closed by a membrane. This was 

 very evidently the case with respect to many of the largest- 

 sized examples we ever met with. They were on the valves 

 of Pinna from island of Coll. The cells were large, and 

 the branches, having full scope, covered about three inches 

 of the shell in length by about an inch and a half in 

 breadth, and many of the cells had this membranous cover- 

 ing of the aperture by a calcareous deposit rendered as 

 thick as the cells. 



