8 THE PKOCEEDINGS OF THE LINNEAN SOCIETY 



polyps. There is simply a fleshy tube with a mouth at the top, 

 and a few small rounded prominences in place of tentacles, four 

 of them sometimes the largest. 



Arachnopora. New Genus. 

 Zoothome parasitic spreading like a small thin web over other 



corals. 



Arachnopora argentea. n. s. 



Zoothome spreading in a small extremely thin web, silvery 

 white, and in parts quite transparent, which are sparsely covered 

 with small silvery granules. The calices are all small very slightly 

 raised, rounded, on which septa protrude as three or six broadly 

 triangular teeth ; calices irregular, but with a tendency to a 

 quincuncial arrangement. Length of zoothome 7, breadth 3 mil. 

 Calices like minute dots, barely discernable to the unassisted eye. 



In this species the substance of the zoothome seems a quite 

 transparent membrance, on which there is generally a very close 

 arrangement of small silvery granules. It occurs parasitic on 

 corals, filling up half of the calice and spreading from opposite 

 septa just like a spider's web. It also spreads over the sides of 

 the costee, where it appears just like a snail's track on which 

 some very fine white dust had been sparsely scattered. There 

 are no calices on the outside. 



On a New Species op Psammoseris. 



By the Rev. J. E. Tenison- Woods, F.G.S., F.L.S., Corr. Mem. 



Linn. Soc. N. S. W. 



Plate I. 



In 1848, Messrs. M. Edwards and J. Haime published in the 

 Annates des Sciences Naturelles a definition of a new genus 

 named Ileterocijathus, which was referred to the second section of 

 the Turbinolian family of corals. The genus thus established 

 was meant to include simple cylindrical corals with a broad 

 attachment always to shells which the base often enclosed, with 



