No. 6] NEW MELOBESIEAE. 11 



jj. long and 9 — 14 jj. broad, the latter 11 — 18 fj. long, and always 

 thin-walled. The perithallic layer is vigorous, with square or up 

 to IV2 times longer than broad cells, or 8 — 18 <j. long and 8 — 11 

 jj. broad. 



The species is only known from the Sandwich Islands. Herb. 

 W. G. Forlow, no. XXXI in part. 



L. dentatum (Kiitz.) Fosl. 

 List of Lith. p. 10. 



f. sandvicensis Fosl. mscr. 



Thallus resembling f. aemidans except the lower branches 

 occasionally being almost terete, the upper and frequently flabellate 

 ones a little thicker, and the central cells shorter than in the said form. 



The solitary and fragmentary specimen that I have seen of 

 this form almost coincides in habit with specimens of f. aemidans 

 collected by me on the west coast of Ireland. However, it differs 

 from typical f. aemidans the lower branches occasionally being 

 almost terete, and the upper which are compressed, more or less 

 broad and flabellate are a little thicker than frequently in the 

 said form. 



With reference to structure the central cells are on a longi- 

 tudinal section frequently shorter than in L. dentatum, and more 

 gradually passing into the perithallic layer. 



L. dentatum is a species very muen varying even in structure 

 and, therefore, I am most inclined to consider f. sandvicensis only 

 as an extreme form of the species. I possess a specimen from the 

 coast of California which in habit almost fully accords with typical 

 L. dentatum f. aemulans and in structure stands between that of 

 the latter and f. sandvicensis. 



The present from has been gathered on the Sandwich Islands 

 by Mr. J. M. Bamard in 1858, herb. W- G. Farlow, no. XXX. 



Subgen. Lepidomorphum Fosl. 



L. torquescens Fosl. mscr. 



Thallus forming subhemispheric or irregular masses of repea- 

 tedly subdichotomous or irregularly divided branches with very 



