Ser. KnoDospEiiMEiE. Pam, Rkodomelacece. 



Plate XXXVII. A. 



HALODICTYON ARACHNOIDEUM, Ham. 



Gen. Char. Frond* tubular (simple or forked) network, formed by nume- 

 rous, inosculating, confervoid filaments ; the meshes irregular, emitting 

 at the angles, free, horizontal ramelli. Fructification : 1, urceolate 

 ceramidia, containing a tuft of pear-shaped spores ; 2, lanceolate sti- 

 chidia, containing a single or double row of tetraspores. — Halodic- 

 tyon (Zanard.), from a\?, the sea, and Scktvov, a net. 



Frons (quasi reticulum tubidosum, simplex v. furcatum) ex fills confervoicleis 

 numerosis angulatim anastomosantibus conflata ; maculis irregular ib us, ra- 

 mellos liorizontales breves ad angulos emittentibus. Frucl. : 1, ceramidia 

 urceolata , fasciculum sporarum pgriformium includentia ; 2, stichidia lanceo- 

 lata, tetrasporas triangule divisas uui-biseriatas foventia. 



Halodictyon arachnoideum ; network compressed, repeatedly forked ; fila- 

 ments arachnoid, the primary articulations cylindrical, 6-8 times as 

 long as broad. 



H. arachnoideum ; reticulo compresso dicliotomo ; filis aracltucideis, articulis 

 primariis cylindraceis diametro Q-8-plo longioribus. 



Hanowia arachuoidea, Harv. in Trans. R. I. Acad. v. 22. p. 558; Alg. 

 Austr. n. 116. 



Hab. Dredged in 6-8 fathoms. King George's Sound ; very rare, W. H. H. 



Geogr. Distr. As above. 



Descr. Network 1-2 inches long, at first decumbent, spreading vaguely over 

 other Algse ; afterwards throwing up erect or ascending branches, which are 

 at first simple, then forked, and finally repeatedly dichotomous. All the 

 axils are remarkably obtuse, and the arms of the forks very patent. The 

 filaments of which the net is composed are excessively slender, not quite 

 cobwebby, but finer than human hair ; the meshes are of unequal size, pent- 

 angular or hexangular, and emit from the angles short, horizontally patent 

 ramuli. These latter usually consist of a single cell. The articulations are 

 all cylindrical, not contracted at the joints, and are filled with rose-coloured 

 endochrome. The fruit has not yet been seen. The substance is delicately 

 membranous, and the frond closely adheres to paper in drying. 



In the present Plate I figure two species of Halodicijon, of 

 both of which I obtained very few specimens, and these mani- 

 festly in a not fully developed state. In a future number I shall 

 have an opportunity of showing, under //. cms f rale, that Sonder's 

 genus " Hanoma" is the same as the earlier Halodictyon, founded 



