ALCYONARIAX CORALS 



131 



servatives or fades away if the coral is dried, and thus in 

 the collections it has the " whitish ash colour " that Clusius 

 describes. 



Primnoa reseda is found in deep water in several localities 

 off the west coast of Scotland, the Shetland Islands, and the 

 Faroe Channel. It is also found in the Norwegian fjords and 

 in the Bay of Fundy on the North American coast. It does 

 not seem to occur in the Mediterranean Sea or in the Tropics. 



There are man}^ genera and species 

 belonging to this family distinguished 

 from one another by the details of the 

 armature of the polyps and other char- 

 acters.^ The polyps are frequently ar- 

 ranged in regular whorls instead of 

 irregularly as they are in P. reseda, and 

 they frequently bend upwards, not down- 

 wards as they do in this species. Two 

 species in which the polyps are thus 

 arranged in whorls have been found in 

 deep water off the Irish coast. Specimens 

 of Caligorgia flabellum, a species with 

 whorls of small polyps which bend up- 

 wards, were obtained from 500 - 700 

 fathoms, and also a specimen of Siaclivodes 

 versluysii, about four feet in length and 

 unbranched, with whorls of large polyps 

 which bend downwards, in 500 fathoms." 



Fig. 59. — Primnoa 

 reseda. A small part 

 of a branch showing 

 the polyps covered 

 with an armature of 

 scales. In this genus 

 the polyps hang down- 

 wards. • :: diams. 



Members of the family Plexauridae, to 

 which reference must be made, differ 

 from the Gorgoniidae in having a thick coenenchym cover- 

 ing the axis, and the branches are consequently relatively 

 thick and coarse (Fig. 60). 



The axis is sometimes purel}^ hornv, but occasionally 

 contains some calcareous granules, and at the swollen base 

 of attachment it is frequently so densely impregnated with 

 calcareous salts that it is as hard as limestone. 



^ J. Versluys, Primnoidae of the Siboga Expedition, 1906. 

 - Jane Stephens, Fisheries, Ireland, Scientific Investigations, 1909, \'. 



