Ser. RhodospermejE. Earn. Rhodomelacece. 



Plate XL. 



THURETIA QUERCIFOLIA, Dne. 



Gen. Char. Frond stipitate ; stipes filiform, inarticulate, branched ; the 

 branches bearing pinnatifid, compressed or flattened, midribbed and 

 penninerved networks, formed of confervoid, anastomosing ramelli. 

 Fructification : 1, urceolate ceramidia springing from the midribs of 

 the network, and containing a tuft of pear-shaped spores ; 2, sub- 

 globose stichidia, sessile on the lateral nerves of the network, con- 

 taining tripartite tetraspores. — Thuretia (Dne.) ; worthily dedicated 

 to M. Gustave Thuret, one of the ablest and most successful inves- 

 tigators of the physiology of the Algse. 



Frons stipitata ; stipes filiformis, inarticulatus, ramosus ; ramis in reticula com- 

 jiressa v. applanata costata et penninervia, ex filis confervoideis anastomosan- 

 tibus formata exeuntibus. Fruct. : 1, ceramidia urceolata, ex cosiis reticidi 

 enata, fascicidum sporarum pyriformhim continentia ; 2, tetrasporce triangule 

 divisee, in stichidiis subglobosis ad nervos sessilibus evolutce. 



Thuretia quercifolia; network flattened, linear-oblong, lobed or subpin- 

 natifid ; the lobes broadly oblong, obtuse, fimbriato-dentate ; articu- 

 lations about twice as long as broad ; ceramidia much acuminated. 



T. quercifolia ; reticido applanato lineari-oblongo lobato autpinnatijido; segmentis 

 oblongis obtusis fimbriato-dentatis ; articulis brevibus ; ceramidiis oreporrecto. 



Thuretia quercifolia, Dne. in An. Sc. Nat. s. 3. v. 2. p. 236. Kiitz. Sp.Alg. 

 p. 673. llarv. in Trans. R. I. Acad. v. 22. p. 537 ; Alg. Exsic. dustr. 

 n. 118. 



Hab. Western and southern shores of Australia. Particularly abundant at 

 Port Phillip Heads, and at Western Port, Mrs. Mallard, W. H. H., etc. 



Geogr. Distr. As above. 



Descr. Root discoid. Stems many from the same base, filiform, cartilaginous, 

 elongate, often spirally coiled round each other, or so interwoven as to be 

 inextricable, naked below and laterally branched ; the branches passing into 

 the bases of the networks, through which they are continued to the summit 

 as midribs. The frond consists of a double system of growth; an axis or 

 skeleton which forms the framework, and a superficial network. The axis 

 is externally inarticulate, but formed (on the plan of a Polysiphonia or 

 Dasya) of numerous longitudinal cells surrounding a central cell. It emits 

 distichously, at intervals of about the tenth of an inch, lateral polysiphon- 

 ous ramuli, which spread subhorizontally, and constitute the nerves of the 

 penninerved frond. Over this closely pinnated framework is spread the net, 

 which is composed of anastomosing confervoid ramelli that issue from the 



