112 The Irish Naluralist. July, 



The least worm-like of all the groups generally included 

 under the term " worms " are the Sea Mats or Potyzoa, 

 which are popularly regarded as akin to sea- weeds. Many 

 of these are found encrusting stones, shells and other 

 objects both in shallow^ and deep water. During the 

 course of various cruises of the Department's steamer 

 much material was dredged, and this yielded a good 

 harvest of Potyzoa. These are described by Mr. Nichols.^ 

 A variety of Brettia pellucida is new to science. 



EcHiNODERMS. — Star-fish, brittle-stars, feather-stars and 

 sea-urchins all belong to one great group of invertebrates 

 (Echinoderma). The shallow- water forms of the Irish 

 marine area are fairly well known, but among the deep-sea 

 species there is still a great field for research. The present 

 report by Mr. Farran^ gives an account of the species that 

 have been taken in depths greater than 50 fathoms. No 

 less than 69 species are enumerated, of which 18 are new 

 to the Irish marine area. Ophiacantha hihernica and 0. 

 densa are new to science. Many others are extremely rare. 



The feather-stars constitute only a small section of the 

 great group of Echinoderma, and Mr. Clark^ of the U.S. 

 Museum in Washington undertook to examine the Irish 

 captures. Altogether there were only eight species, but 

 two of these proved to be new to science. The genus 

 Atelecrinus, to which one of these belongs, had never been 

 observed outside the tropics, and the new species A. Helgae 

 seems to be nearly related to the West Indian A. 

 halanoides. 



CoELENTERATA. — A curious case of " symbiosis," as it 

 is called, or " living together " of two very distinct forms 

 of animal life was discovered during these investigations. 

 Dr. Ritchie* noticed that what were apparently blisters on 

 a deep-sea mollusk were in reality the early stages of a 



1 Nichols, A. R. — Polyzoa from the Coasts of Ireland. Fisheries, 

 Ireland, Sci. Invest., 1910, i. [1911]. 



2 Farran, G. p. — The deep-water Asteroidea, Ophiuroidea and 

 Echinoidea of the West Coast of Ireland. Fisheries, Ireland, Sci. Invest. 

 1912, vi. [1913]- 



^ Clark, Austin H. — On a collection of recent Crinoids from the waters 

 about Ireland. Fisheries, Ireland, Sci. Invest., 1912, iv. [1912]. 



* Ritchie, James. — A new British Commensal Hydroid, Perigoniraus 

 abyssi, Sars. Fisheries, Ireland, Sci. Invest., 1913, i. [1913]- 



