234 MESSES. W. WEST AND G. S. WEST ON 



This species was in great abundance, and seems veiy cliaracteristic, as tlie filaments- 

 are of a more uniform breadth throughout than are those of any other species belonging 

 to the subgenus Bidywoprium. 



Genus Dociditjm, Breb. 



16. D. Baculum, Breb. in Kalfs, Brit. Desm. p. 158, tab. 33. fig. 5. 



Long. 296-348 f* ; lat. ad has. semicell. 12*5~13 /a; lat. ad medium semicell. 9"6 {l. 



The description and figure given by Wolle (Desm. U.S. p. 49, pi. 11. figs. 3, 4) do not 

 belong to this species. This cosmopolitan species is always constant in its characters, 

 always having a basal inflation with a slight constriction immediately above it and 

 the plications at the base. The Locidium Bactdum recorded by Prof. F, L. Harvey from 

 Maine (in Bull. Torr. Bot. Club, vol. xix. Apr. 1892, p. 122) is not that species, as he 

 refers it to WoUe's figure, and his measurements (long. 425 (h, lat. 2q (/j\) are much too 

 large. We give a figure (PI. XII. fig. 35) of the largest specimen we have ever seen 

 (and that an American one) ; the breadth of this species is fairly constant. 



Genus Pleueot^nium, Nag. 



17. P. NODOSUM, Lund. Desm. Suec. p. 90. [Docidiiim nodosum, Bail, in Balfs, Brit. 



Desm. p. 218, t. 35. fig. 8.) 

 North American examples of this species attain very much larger dimensions than do 

 British forms. A figure is given (PI. XII. fig. 31) of an abnormal semicell (long, semi- 

 cell. 329 jO. ; lat. ad bas. infl. 67 ^ ; lat. apic. 41 (Jj) possessing an extra nodose projection 

 on one side, causing the semicell to be bent at that point. 



18. P. CONSTRICTLM, Lagerh. in Ofvers. Sv. Vet.-Akad. Forh. (1855) n. 7, p. 251. 



{Bocidlum constrictum. Bail, in Halfs, Brit. Desm. p. 218, t. 35. fig. 7.) 

 Long. 415-500 ^ ; lat. ad bas. semicell. 41-48 jM. ; lat. apic. 26-30 (l. 

 The constrictions of the semicells of this species vary considerably in depth in difi*erent 

 examples. Sometimes the two semicells of the same plant are differently constricted ; in 

 one specimen the breadth across the constrictions of one semicell was 40 — 36 — 34 ^i, and 

 that across those of the other only 33 — 31 — 26 /«. The number of constrictions present 

 on a semicell may be either 3 or 4. The apical papillso are also subject to considerable 

 variation ; in some cases they are mere rounded granules, whereas in others they are long 

 and very sharp teeth. 



19. P. HYPOCYMATiuM, nov. sp. (PI. XIIl, fig. 1.) (? Bocidium Baculum, Breb. var. 

 flondense, Wolle, Alg. U.S. p. 26, pi. 54. fig. 5.) F. parvum, circiter 28-plo longius 



quam latins, vix attenuatuin, lateribus leviter undulatis, undulis apices versus 

 gradatim minoribus, lateribus infra apices rectis ; apicibus subtruncatis granulis 4 

 (visis) juxta marginem ornatis ; mcmbranfi minute et irregulariter punctata. 



Long. 396 {l ; lat. ad bas. semicell. 16 ^ ; lat. apic. versus 12'5 ^. 



We have seen this species not un frequently ; it may be compared with P. cmnulatum 

 and P. basiundatttm. West. 



