94r ANTHOZOA HYDROIDA. 



I have a specimen of PL cristata gathered in Cork Bay, and pre- 

 sented to me by J. V. Thompson, Esq., which is nearly three inches 

 in height, spreading laterally, the rachis divided in a regular dicho- 

 tomous manner, and rough or muricated on one side, wherever it is 

 naked of pinnae. The vesicles have from seven to nine crested ribs, 

 with a spinous dorsal keel. The roughness of the rachis is pro- 

 duced by the remains of the deciduous pinnae. I give a figure of 

 this specimen (Plate XXIV. fig. 1 ) as an additional proof that little 

 reliance can be placed on external habit as a character in deter- 

 mining the species of this order. 



Another variety imitates the habit of PI. pennatula. The cells in 

 it have a strong process on the distal side, which, springing from 

 near the middle, projects beyond the rim ; and the vesicles are larger 

 and more numerously ribbed than is usual (Fig. 16). This variety, 



which Mr. Couch has also noticed, appears to be a denizen of deep 

 water. My specimen was dredged in 30 fathoms, by Professor E. 

 Forbes, off the Isle of Mull. 



3. P. PENNATULA, pennated ; cells approximated, cup-like 

 with an unequally-crenated margin, supported on the under 

 side ly a lengthened incurved spinous process. G. Montagu. 



PLATE XXII. Fig. 1, 2. 



Sertularia pennatula, Ellis and Sdand. Zooph. 56, tab. 7, fig. 1, 2. Fleminy in Edin. 

 Phil. Journ. ii. 83. Aglaophenia pennatula, Lamour. Cor. Flex. 168. Krauss 



