538 



CYLINDIKECIIDJi:. 



Fig. 29. 



C. ■pusiUum. 



This is a very small species^ with a slender cell^ which 

 decliues very markedly to one side on the retreat o£ the 

 polypide. The walls of the zo- 

 cecium have the appearance, 

 under a high power, of being 

 coated with minute granules. 



The creeping stem dilates 

 slightly and gradually at the 

 base of each of the erect tubes ; 

 the expansion thus formed con- 

 stitutes the lower extremity of 

 the cell ; and into the decum- 

 bent portion of its dwelling the 

 polypide, during complete re- 

 traction, is partially withdrawn. 



This is an inconspicuous form, which is to be found 

 creeping over the roots of Laminarice near low-water 

 mark. It has all the characters of a typical member of 

 the genus, but diflPers from its congeners in its minute size 

 and delicate habit and the small number of its tentacles. 

 I have met with a still minuter form (Plate LXXX. 

 fig. 9), bearing a close general resemblance to the pre- 

 sent, of which it may perhaps be a dwarf variety. It is 

 often extremely difficult to examine the minuter Cteno- 

 stomatous species, not merely on account of their size, 

 but from the nature of their habitats ; and I have little 

 doubt that many exist on our shores which have, so far, 

 escaped detection. 



Habitat. On tangle-roots &c. wathin tide-marks. 



Localities. The Castle rocks, Salcombe; tlie Capstone, 

 Ilfracombc (T. H.) 



