296 PLUMULARIID^E. 



but there is no constancy in the number ; and I have seen 

 specimens in which the internodes were short, as in P. se- 

 tacea*, and bore only one. Dr. Johnston assigned three 

 pinnse to each internode, and relied mainly on this cha- 

 racter as a distinctive mark of the species; but on the 

 same shoots the number often ranges from two to five. A. 

 much safer criterion is to be found in the nematophores, 

 which are scantily developed and exhibit a very peculiar 

 structure. They are not pedunculated as in the other 

 species, but consist of minute cup-shaped processes that 

 are immediately attached to the side of the pinna, one 

 below each calycle. 



When present, the reproductive capsules afford another 

 good specific character; they are never axillary, but are 

 produced in rows along each side of the central stem. 

 They are irregular in shape, somewhat ovate, and generally 

 more or less spinous at the top. The male are smaller and 

 much less numerous than the female ; both sexes occur on 

 the same stem. 



Hub. On shells, stones, seaweed, &c., from low-water 

 mark to deep water; common. It ranges from Cornwall 

 to Shetland, and is generally distributed. The deep-water 

 specimens are of the largest size. 



2. P. SETACEA, ElllS. 



"SEA- BRISTLES," Ellis, Corall. 19, pi. xi. figs, a, A. 

 COKALUNA SETACEA, EUis, Corall. pi. xxxviii. fig. 4. 

 SERTDLAUIA IMNNATA /3, Linn. Syst. 1312. 

 SETACEA, Pall. Elench. 148. 



* It. must be remembered that in P. sctacca there is never more than one 

 pinna to an intcrnocle; the nilc in the case of P. pinnata is that there are 

 several. 



