p 6 t e I s i a 269 



The nearest relatives of the present genus 

 are obviously Laminaria and Cymathere. Phyl- 

 laria also is similar in appearance but has 

 numerous cryptostomata on the lamina which 

 are wanting in Renjrewia even when young, 

 Cymathere differs in the folded lamina. The 

 various species of Laminaria have forking sec- 

 ondary hapteres. Evidently the lack of hap- 

 teres, mucilage ducts and strengthening tissue, 

 together with the simplicity of its body, mark 

 this as one of the most primitive of kelps repre- 

 senting a form close to the original ancestor from 

 which all kelps, with the possible exception of 

 the aberrant Chorda and Adenocystis, have been 

 derived. 



The two species with simple holdfasts, 

 previously described as Laminarias are both 

 distinct from the present species. 



Laminaria solidungula J. G. Agradh. (De 

 Laminariaceis Sym. Of. p. 8. 1867.) which is 

 very completely described by its author, pre- 

 sents several points of divergence. It is con- 

 siderably larger than Renjrewia parvula and 

 has well developed mucilage ducts. Its habit 



