PRESERVATION OF THE HYDROIDA. 153 



"to be between tide marks on the south coast, and mentions 

 a circular groove near the base of the body as a means of 

 identification. 



Perigonimus sessilis. 



The only species with ringed coenosarc. The polyp not dilated 

 underneath the tentacles. 



Bougainvillea muscus. 



Allman distinguishes this species by its small, habit and the 

 fact that its stems consist of a single tube, instead of being 

 composed of several tubes coalesced into one. The records for 

 this species seem to be very scanty. 



Clytia Johnstoni. 



The pedicel in this species is usually ringed at the top and at 

 the bottom, being smooth in the middle portion. Some specimens 

 are, however, more or less ringed throughout. 



Obelia geniculata. 



This species is readily distinguished by the projections sup- 

 porting the ringed pedicels bearing the hydrotheca. 



Campanularia neglecta. 



The margin of the calycle in this species is crenulate. This 

 can only be seen with difficulty, as it is so readily damaged. 



Halecium Beanii. 



It may be easily identified when bearing female capsules by 

 their distinctive shape and the short tubular orifice in the middle 

 of the capsule. 



Sertularia filicula. 



This hydroid varies in the position of the calvcles on the stem, 

 some being placed oppositely, and some more or less alternately. 

 It may be distinguished by the single erect calycle in the axils 

 of the branches. It is a deep-water species (20 fathoms), and 

 more especially a northern species. Hincks never met with it 

 in Devon or Cornwall, so its occurrence in rock-pools at Sidmouth 

 is somewhat noteworthy. 



Jourx. Q. M. C, Series II. No. 73. 11 



