REPORT ON THE ALCYONARIA. 3 



The longitudinal ribs which mark the wall of the axial and secondary polyps are due 

 to a thickening of the middle spicule-bearing layer. Their position is always between 

 two mesenteric folds, while the intermediate furrows correspond in position to the same. 

 Nutritive canals and endodermic tubes are not demonstrable in the older portions of the 

 axial polyps. These first appear where the net of spicules becomes loose, and are finally 

 lost in isolated calcareous bodies ; there they unite the secondary polyps with the 

 cavities of the axial polyps. 



Along with the foregoing description of this species it should be mentioned that, in 

 those parts of the colony which are free from the parasitic sponge, the lateral polyps 

 appear tubular, and stand free from the axial polyps at an acute angle. They exhibit 

 longitudinal striation, and reach a length of from 2 "5 to 4 mm., with a breadth of from 

 1 to 1*5 mm. 



Family Alcyonid^, Verrill. 

 Sarakka, Danielssen. 



Sarakl-a, Danielssen, Norske jSTordhavs-Exped., 1876-78, Zoolog., Alcyonida, p. 118, 1887. 

 Sarakka crassa, Danielssen, loc. cit., p. 112. 



A small polyp colony in the Challenger collection agrees so exactly with Danielssen's 

 excellent figure and description, that I identify it, without doubt, as belonging to this 

 species. From a broad lobed base, growing upon foreign bodies, the colony attains 

 a height of about 16 mm., dividing into two thick branches, from which short lobed 

 twigs are given off, thickly beset with polyps at their ends. Stem and branches 

 are hard and rigid, with longitudinal grooves. 



The colour, in spirit, is yellowish white. The form of the polyps and of the spicules 

 agrees, in all particulars, with Danielssen's description. 



Habitat. — Stations 135 a-c ; off Tristan da Cunha ; 100 to 550 fathoms ; hard ground, 

 shells, gravel. 



Danielssen's specimen was obtained by the North Atlantic Expedition at Station 

 31 ; lat. 63° 10' 5" N, long. 5° E.; 417 fathoms ; bottom, sandy clay. 



Family NephthyiD/E. 

 Subfamily Siphonogorgist^e. 



Siphonogorgia, Kolliker. 



Three more species of this interesting genus were subsequently found among the 

 Challenger gatherings ; these extend the compass of the genus to seven species. The ex- 

 amination of these specimens fully confirms the formerly expressed opinion that the genus 



