468 



being but slightly narrowed or not at all; upwards the narrow- 

 ing of the branches is, for the most part, slight and gradual until 

 rather suddenly, near the summit, they start tapering rapidly 

 into the acute apex. 



As described by COLLINS and HERVEY the tetrasporangia 

 are formed in the upper ends of the branches (Fig. 426 a); the 



fructiferous part is swol- 

 len being often about 

 twice the breadth of the 

 sterile, slender part. 



In several respects, 

 for instance, as to its 

 whole appearance, this 

 plant shows great like- 

 ness to the Laurencia 

 chondrioides described by 

 me, but on closer ex- 



Fig. 426. Ckondria polyrhiza Collins and Her- 

 vey. a, part of thallus with a group of rhizoids 

 and a tetrasporic branch, b, transverse section 

 of the thallus. (a, about 17:1; b, about 60:1.) 



amination several differ- 

 ences will soon be obser- 

 ved, for instance, the 

 acute apex of the thallus, 

 the pericentral cells easily seen through the cortical layer, the 

 different shape of the branches especially the tetrasporic ones 

 and the highly deviating transverse section. 



Found with tetraspores in the month of March. 

 The specimens were gathered in the same locality as those formerly 

 examined. 



St. Jan: off Cruz Bay. 



120. Chondria atropurpurea Harv. 



121. littoralis Harv. 



122. dasyphylla (Woodw.) Ag. 



123. Acanthophora spicifera (Vahl) B0rgs. 



124. muscoides (L.) Bory. 



125. Polysiphonia havanensis Mont. 



126. 

 127. 

 128. 

 129. 

 130. 



spec. 



variegata. (Ag.) Zan. 

 sphserocarpa B0rgs. 

 macrocarpa Harv. 

 ferulacea Suhr, J. Ag. 



