MARINE FLORA OF SOMERSET. 117 



in my Minehead plants the ordinary cells are slightly con- 

 stricted at the dissepiments, a peculiarity which he had not 

 before remarked, and proving to him that Cladophora 

 Gattyae, figured at t. 355, b. of the " Phycologia," is 

 an Ectocarpus, and he believes this very plant in a young 

 State. Ectocarpus tomentosus has the same habitat as 

 E. llttoralis, and often grows intermixed with it. By the 

 naked eye E. tomentosus may be distlngulshed from the 

 latter by its much finer filaments, resembling in size those 

 of E. siliculosus,* but usually more intertwined and twisted 

 together than in this plant. The fruit when yiewed through 

 the microscope is seen to be very dlfferent from that on 

 E. littoralis. It consists of obtuse and linear oblong silicules, 

 supported on little pedicels. In E. siliculosus the sUicules 

 are drawn out and very acute at the tips. 



Proceeding to the Red Series in the first tribe (Rhodo- 

 melace«), two species of Polysiphonia clalm our notice ; 

 the one, P. nigrescens, grows commonly intide pools along 

 the coast ; and the other, P. fastigiata, abounds on its usual 

 habitat, the old fronds of Fucus nodosus. In the next 

 tribe (Laurenciacete), we have only Laurencia phmatifida, 

 rarely found at T^Iinehead, but common in the pools on 

 Bosslngton beach. CoraUina officlnalis, belonging to that 

 curiour tribe of algte whose tissues are firmly encased in a 

 coating of carbonate of llme, is extremely abundant in all 

 pools along the shore. In the Rhodymeniaceas we cannot 

 reckon with certainty, more than Gracilaria confervoldes, 



* In salt-water ditches, near SHrehampton, Gloucestershire, Mr. 

 Thwaites Jiscovered a species (Ectocarpus amphibius, Harv.) wth fruit 

 intermediatein character between that of E. littoralis and E. siliculosus. 

 It does not appear to havc been observed in Somerset. In the salt- water 

 ditches on the Norfolk coast it is noted as "not unfrequent I have 

 looked invainfor it in the tide ditches at Minehead. E. sihculosus I 

 SQmetimcs see growing with E. littoralis. It appears however in such 

 a poor condition and so rarely that it seems hardly to deserve notice. 



