Addenda.— Of tbe specimens received from Mr. Lawson, some iiKlividiials 

 are younger than either of Dr. Blake's. In these the polyp-rows are farther 

 apart, and there are not so many polyps in the row ; neither do the ends of the 

 rows approximate so closely on the side opposite the axial edge ; the polyps being 

 not nearly so many in the same length, or presenting (as do some of Dr. Blak-e's 

 specimens) so crowded an appearance. In cross-section through the polypiferous 

 piM-tions, the younger individuals are less ovate or acutely oval than inthe older 

 specimens. The general aspect of this species, judging from the figure in Plate 

 XXXI. of Johnson's British Zoophytes (2d ed.), is like P. qmidrai}<yulnrts from 

 Oban. 



