230 SEAWEEDS 



the carpospore, the early stages of which may be 

 seen represented in Fig. 73. 



The Geographical Distribution of the family is a 

 wide one throughout both the north and south 

 temperate zones and the tropical belt. Representa- 

 tives penetrate also into the colder waters. Rhody- 

 mcnia, Cordylecladia, Lomcntaria, Champia, Chyloda- 

 dia and Plocamium are all British and for the most 

 part abundant on our shores. 



Dclessericce. 



This family includes a number of the most 

 beautiful red seaweeds, if indeed they are not the 

 most beautiful of all Algae. They possess leaf-like 

 fronds, some of them with midribs (Dclcsscria) others 

 with delicate lace-like or net-like expansions (Claudea, 

 Martensia, Vanvoorstia, genera formerly reckoned 

 among the Rhodomelew) and are all notable for their 

 conspicuous and graceful forms. Nitophyllum and its 

 immediate allies (see p. 202) differ from most other 

 Rhodophyccw in the occurrence of subsequent interca- 

 lary divisions of the thallus filaments. The procarpia 

 are situated in the middle layer of the fronds, and the 

 gonimoblast produces the carpospores within a fruit 

 cavity formed of the thickened cortical layer of the 

 thallus, perforated in the centre for the escape of the 

 spores. The gonimoblast is somewhat indistinctly 

 divided into several lobes, formed simultaneously or 

 in succession, which bear the carpospores singly or in 

 series terminally, or more rarely almost all the cells 

 form spores. 



