No. 3] FIVF NEW CALCAREOUS ALGÆ. 5 



The conceptacles of sporangia as well as those of cj^stocarps 

 nearly agree with the similar organs in L. fasciculdtum. 



A longitudinal section of a branch shows cells which com- 

 monly are 12 — 20 /-/- long and 7—10 \). broad. 



Old specimens of the present species approaches L. fascicu- 

 latum f. subtilis in habit, but is separated by essential characteristics. 



It is known from the pacific coast of middle Japan, Marine 

 Laboratory at Sagami province. K. Yendo no. 80, 120, 270, 379, 

 382, 389, and 408. 



Lithophyllum zostericolum Fosl. mscr. 

 f. tenuis Fosl. mscr. 

 f. mediocris Fosl. mscr. 



It has been rather uncertain how the Alga described by 

 Harvey as Melobesia amplexifrons vvas to be understood. Two 

 somewhat different forms have been referred to it by me as well 

 as other botanists. However, through the kindness of Dr. E. P. 

 Wright I have had the opportunity to examine an authentic spe- 

 cimen from Port Natal of this in the southern hemisphere appa- 

 rently widely dispersed species. From this specimen is to be seen 

 that the true M. amplexifrons Harv. is a Lithophyllum, as for- 

 merly considered, agreeing with the plant delineated by Rosanoff, 

 Rech. Melob. pl. VII, hg. 2 — 3. It frequentty surrounds other and 

 cylindrical Algæ, especially Oelidium, and attains a thickness of 

 up to about 0.A mm. 



The other, for which i propose the above name, differs from 

 L. amplexifrons especially by its much thinner crust and smaller 

 cells. It appears frequently to stick to Zostera. 



In f. mediocris the crust attains a thickness of up to about 

 150 fi, in f. tenuis about 60 fi. The former at first forms sub- 

 orbicular, at length confluent and rather irregular patches on the 

 host, but in the latter the delicate and minute crusts do not always 

 fully anastomose, and sometimes the one crust stretches itself over 

 the other. 



