THTJIARIA ARTICULATA. 277 



whilst a line of calycles winds round it spirally from top 

 to bottom. A single joint also occurs on the branches a 

 little above their origin ; and it is at this point that they 

 break off, leaving the basal portions, which form the knots 

 that roughen the denuded section of the stem. 



The " brush " varies in size, and is sometimes of con- 

 siderable length. When fresh, it is of a fine reddish-brown 

 colour, and contrasts well with the dark shining stem. 

 The young is simply pinnate. The long, bare stalks of 

 Thuiaria thuja offer a fine field for settlers, and are com- 

 monly occupied by a large foreign population ; they are 

 often encrusted by CeUepora and Alcyonium, and over- 

 spread by the delicate network and minute cups of the 

 smaller Hydroida (Lafoea, Filellum, &c.) . 



Hob. On shells &c. from deep water. A prevalent 

 northern form, ranging to the North Cape. The finest 

 specimens I have seen were from the Dogger Bank ; they 

 were remarkable for the great length both of the stem and 

 brush. South Devon (Turton and Kingston): Cornwall, 

 very rare ; from deep water, Polperro (Couch) . 



[Mediterranean (taste Pallas): Tromso and North Cape 

 on shells (Pecten Islandicus &c.) in 30-40 fath. (Sars): 

 Gulf of St. Lawrence (tests A. Agassiz): a Thuiaria re- 

 sembling T. thuja is found, on the authority of Stimpson, 

 in Behring's Straits.] 



2. T. AETICULATA, Pallas. 



" SEA-SPLEENWORT or POLYPODY," Ellis, Cor. 11, pi. vi. 



SERTULARIA ARTICULATA, Pallas, Elench. 137 ; Etper, Pflanz. Sei't. t. viii. 



figs. 1,2. 



,, LONCHITIS, Ellis # Soland. Zooph. 42. 



CELLARIA LONCHITIS, Lamk. An. s. Vert. (2nd ed.) ii. 186. 

 TIIUIARIA ARTICULATA, Fletii. Br. An. 545 ; Johnst. B. Z. 84, pi. xviii. figs. 3, 4. 

 NIGELLASTRUM ARTicuLATUM, Oken, Lelirb. Nat. 93. 



Plate LX. 

 SHOOTS simple or irreijulnrly divided; STEM very slightly 



