Laing. — On Neic Zealand Species of Ceramiacese. 385 



least sufficiently full and accurate to enable any subsequent inves- 

 tigator to determine what plant I have had under investigation. 

 The cell-dimensions given were obtained from specimens 

 mounted in glycerine jelly, and variously prepared. They may 

 therefore differ from those that would have been obtained from 

 the measurement of fresh specimens. They should, however, 

 at least be relatively correct. 



Order FLORIDE^. 



Fam. CERAMIACESE. 



The thallus consists of single branched cell filaments, some- 

 times with an adventitious cortex formed of rhizoids. This 

 false cortex is produced in the genera allied to Callithamnion by 

 the outgrowth of the rhizoids from the basal cell of lateral 

 branches. In Ceramium and its immediate allies such filaments 

 spring from the upper ends of the cells of the thallus, thus 

 forming a peripheral crown of cells covering the place where the 

 parent cell is joined to the one above it. In some cases the 

 filaments clothe the main cell row, in others they fail to meet, 

 and leave the intervening parts bare. The sporangia are solitary 

 or distributed in groups over the thallus, or confined to special 

 branches, either placed externally on the thallus or hidden in the 

 cortex. The tetraspores are generally in tetrads, but sometimes 

 variously divided. The antheridia are distributed in very varied 

 form over the thallus, and contain generally many tightly packed 

 spermatangia. The carpogonia bearing branches and those bear- 

 ing the auxiliary cells are generally united in special procarps of 

 various arrangement. The cvstocarps are, as a rule, scattered 

 over the upper part of the thallus, or more or less deeply sunk 

 or completely buried in the cortex. The gonimoblasts (of which 

 there, are usually two in each cystocarp) form successively several 

 lobes, of which nearly all the cells give rise to spores. The cysto- 

 carp if external is entirely naked, or covered only by an involucre 

 of short incurved branchlets. 



Key to the New Zealand Genera. 



A. The branches of the thallus consisting of single rows of cells. 



(a.) Speemothamnie^;. — Thallus naked or provided with very 

 delicate verticillate ramuli.* Cystocarps terminal on special fertile 

 branches. The fruit-mass of 1 or 2 gonimolobes. 



(i.) Thallus with creeping rhizoids and upright laterally 

 branched fertile shoots. Fruit-mass with 2 gonimo- 

 blasts . . . . 1. Spermothamnion. 

 (ii.) Thallus with creeping rhizoids and upright oppositely 

 or alternately pinnate fertile shoots. Fruit-mass with 

 1 gonimoblast . . . . . . 2. Ptilothamnion. 



* The term " ramuli " has been used throughout this paper to denote short limited 

 branchlets, frequently in whorls at the nodes (Ger. Kurztrieben) . 



25— Trans. 



