402 Transactions . — Botany . 



Distribution. — Common along the coast of the South Island, 

 and probably elsewhere ; Australia, South America. 



I have examined one of Professor Harvey-Gibson's type 

 specimens of Rhodocorton parkeri, and I have no hesitation in 

 saying that it is a very young specimen of this plant. The 

 spines, which, according to Professor Gibson, in his plant " form 

 the most characteristic and diagnostic feature of the species," 

 are equally characteristic of B. scoparia. The segmentation of 

 the cells is that of B. scoparia, and not of a Rhodocorton. The 

 arrangement and division of the tetraspores is the same in each. 

 Specimens of each are indistinguishable in their appearance 

 under the microscope ; the relative dimensions of the cells are 

 the same, and rhizoids are developed similarly on both. Rhodo- 

 corton parkeri was found at the base of a thallus of Lychaete 

 darwinii* Lychaete danvivii and Ballia scoparia are found so 

 frequently epiphytic one upon the other that their constant 

 companionship seems almost to suggest commensalism. Appar- 

 ently, then, there is every reason for regarding R. parkeri as 

 merely a synonym for B. scoparia. 



Genus 10. Antithamnion. 



Thallus filamentous, generally dichotomously branched with 

 sympodial growth. The main axis consists of single rows of cells 

 with opposite or whorled generally richly branched ramuli. On 

 the branches of the ramuli are often formed peculiar gland-cells. 

 The sporangia are terminal on the branches of the ramuli, and 

 divide cruciately. The antheridia are small bundles of branches 

 terminal on the ultimate branch of the ramulus. Fertile ramuli 

 are distributed over the shoot or collected in bundles close to its 

 end. The development of the terminal cells is then arrested. 

 The cystocarps thus become nearly terminal or apparently ter- 

 minal. They are enclosed as with an involucre by the upper- 

 most sometimes subsequently developed ramuli. In some spe- 

 cies the sporangia-bearing plants develop paraspores in few- or 

 many-celled irregular masses at the point of the shoot. 



1. Antithamnion applicitum, R. M. L. (= Callithamnion appli- 

 citum, Harv., Fl. N.Z., ii., 258). Plate XXX.. fig. 2. 



Thallus minute, investing the surfaces of other algae but 

 not completely attached to them. Fronds 2-3 mm. in height, 

 partially erect, nearly regularly oppositely pinnately distich- 

 ously branched. A pair of pinnae spring from below the apex 

 of each cell and from opposite sides of it: these are generally 

 compound, sometimes decompound. The pinnules are arranged 

 similarly to the pinnaa, and both pinna? and pinnules consist of 



* Laing, Trans. X.Z. Liist.. vol. xxvii.. p. .'500. 



