of South Devon and South Cornwall. 257 



4. P. pennatula, Ellis & Solander. 



Very rare : first recorded as a Devon species by Montagu, in 

 a letter to Dr. Fleming, in 1808. 



A single plume, given to me by a friend, which was obtained 

 at Teignmouth, is the only Devonshire example which I have 

 seen. It is a peculiar variety, measuring about three-quarters 

 of an inch across, and much less delicate and feather-like than 

 the ordinary form. 



Cornwall, from the Corwich Crab and the stems of Laminaria 

 digitata (C. W. Peach). 



5. P. myriophyllum, Linn. 



Not common : occasionally amongst the trawl-refuse ; Fly- 

 mouth Sound [Bellamy). 



6. P. pinnata, Linn. 



Common : dredged in moderate depths ; trawled off Budleigh- 

 Salterton, of large size, &c. 



7. P. setacea, Ellis. 



Very common between tide-marks, and dredged in moderate 

 depths. The large, branched variety, several inches high, is 

 obtained on the coast of Cornwall. 



8. P. echinulata, Lamk. PI. VII. figs. 5, 6. 



Very abundant in tide-pools and the Laminarian zone ; 

 showing a predilection for Zoster a marina and Chorda filum. 



9. P. similis, n. sp. PI. VII. figs. 3, 4. 



Plumose, pinnae alternate, one to each internode, internodes 

 long. Cells large, curving outwards towards the top, entire, 

 separated by two joints ; a single tubule a little below each 

 cell. Gonothecse elongate, smooth, many-lobed. 

 Abundant : on weed in the Laminarian zone. 

 [Isle of Man.] 



This species is most nearly allied to the P. echinulata of La- 

 marck, from which, however, it differs in size and general habit 

 as well as in the minute characters. 



The plumes attain a height of about an inch and a half, and 

 are of much laxer habit and less graceful than those of P. echi- 

 nulata. Each of the internodes into which the stem is divided 

 bears a pinna, which originates a little below the joint. The 

 internodes are long, about half as long again as those of P. echinu- 

 lata. The joints of the two species present a very different ap- 

 pearance (PI. VII. figs. 3, 6). In P. similis the internodes are 

 of about equal width throughout ; in P. echiiiulata they are 



Ann. &> May. N. Hist. Ser. 3. Vol. viii. 17 



