238 CERAIMIACE^. v. 



xindividetl, running through the frond, set throughout with alternate, spirally- 

 inserted, lateral, sub-horizontal branches directed to all sides, the lowest longest, 

 the rest successively shorter ; the whole frond pyramidal. Both the stem and pri- 

 mary branches are filled with veins, which render their articulations more or less 

 obscure. Branches undivided, one to two inches long, attenuated upwards, and 

 copiously furnished throughout with short, very flaccid, capillary or byssoid, dicho- 

 tomo-multifid branchlets directed to every side ; the ultimate divisions of these are 

 almost cobwebby. I have not seen proper teiraspores ; but their place is generally 

 supplied by the conversion of the ultimate ramuli into strings of spores ; affording 

 a mark by which this species is most easily recognised. AVhen first I described 

 this fructification (in Hook. Journ. I. c.) I regarded it as an abnormal development, 

 and perhaps correctly, though more recently (in the Phycologia Britannica) I 

 adopted another opinion, and thereon founded the genus Seirospora. If the strings 

 of seirospores be abnormal, however, they are, so far as I know, only found in this 

 species, and are very constant, characterising it on the shores of England, Ireland, 

 Scotland and Sweden, as well as on those of North America. I am indebted to Dr. 

 Roche of New Bedford for most beautiful specimens, which are identical with the 

 most luxuriant of my English ones. 



Sect. 4. Cruciata : Fronds setaceous or capillary^ alternately decompound, articulate; 

 each node bearing a pair of opposite, minute, simple or compound ramuli. Tetra- 

 spoi^es cruciate. 



11. Callithamnion plumula, Lyngb. ; stems alternately decompound or sub- 

 dichotomous, articulated ; each articulation bearing a pair of short, recurved, pec- 

 tinate or bi-pectinate ramuli ; teti'aspores borne on the tips of shortened ramuli, 

 cruciate. J. Ag. Sp. Alg. 2, /;. 2y. Harv. Phyc. Brit. t. 242. Kiitz. Sp. Alg. 2, p. 

 647. Conferva Plumula, Ellis. — Dillw. t. 50. Conf. Turneri, E. Bot. t. 1637- 



Hab. Longbranch, New Jersey, Miss E. C. Morris, (v. v.) 



Of this beautiful species I have only seen a solitary, ill-dried and faded North 

 American specimen. It is at once known from C. Americanum, which is sometimes 

 mistaken for it by collectors, by the very patent or recurved ramuli, closely pectinated 

 on their upper margin only, with secund pinnellae. 



12. Callithamnion Americanum; filaments elongate, capillary, many times alter- 

 nately decompound, closely and densely or sub-distantly branched, plumose ; ramuU 

 in pairs from every node, opposite, patent, very slender, pinnellate or bi-pinnellate, 

 the pinnules opposite or secund ; lower articulations of the stem eight or ten times, 

 upper four or five times as long as broad ; articulations of the ramuli four to six 

 times as long as broad ; tetraspores elliptical, cruciate, sessile ; favella3 in pairs on 

 the upper branches. (Tab. XXXVI. A.) 



