PEROPHORA ANNECTENS. 57 



some specimens, and as few as sixteen in others, the 

 shortest ones often beino- so short as to be nothing more 

 than buds that can be seen only by the aid of consider- 

 able magnification. It seem.s to me not at all impossible 

 that new tentacles are constantly being formed for a long 

 time after the individual animals have reached the adult 

 condition. There is an evident tendency in some cases 

 for the shorter and longer tentacles to alternate, though, 

 as already said, the circles of shorter and probably younger 

 ones are always nearer the orifice than are the circles of 

 longer ones. 



a. PARASITES OF THE TENTACLES. 



At this point may be described an interesting tentaculif- 

 erous infusorian that occurs parasitic on the tentacles and 

 neighboring inner surface of the branchial siphon, usually 

 on or near the peripharyngeal band. A group of the in- 

 fested tentacles and a few of the parasites on the peri- 

 pharyngeal band are shown in fig. i6, pi. ii, and a single 

 tentacle is shown, more highly magnified, in fig. 17, 

 pi. ii. The impression received at first sight is that one has 

 before him abnormally shaped ciliated tentacles, the cilia 

 being disposed in tufts. As seen by the figures, each 

 tentacle is club-shaped, the terminal knob bearing a tuft 

 of the coarse, usuall}^ long cilia. Besides the terminal 

 knobs there are numerous others scattered irregularly on 

 the sides of the tentacles, also bearingf the cilia in most 

 cases, though not always. As just stated, most of the 

 cilia are long. Not unfrequently. however, tufts are seen 

 in which they are short and distinctly clavate (fig. 17). 

 These latter are generally more numerous in each tuft 

 than are the longer ones. Almost without exception the 

 knobs, whether at the ends of the tentacles or on their 

 sides, or on the peribranchial band, contain from one to 

 several verv distinct round cells, each cell having an 



