HALOCORDYLE COOPEEI. 73 



On Halocordyle cooperi sp. nov., a Hydroid 

 from the Natal Coast. 



By 



Ernest Wni-rcn, D.ISc.L.oiid., 



Director of the Natal Governuient Musenm. 



With Plate IX. 



The hydroid was found at Scottsburg, Natal, in the rock 

 pools near low water. It occurs generally among the sea- 

 weeds, etc., covering polych^t worm-tubes, especially old 

 disused tubes, which often become much encrusted with 

 many forms of plant life, sponges, tunicates, etc. 



(1) Trophosome. — The trophosome possesses a creeping, 

 branched hydrorhiza from which upright stems (fig. 1) arise. 

 They may attain a height of 2 inches or more. The main 

 stem curves gradually from base to summit, and is slightly 

 zig-zag from right to left, where the lateral or primary 

 branches are given off alternately in a regularly distichous 

 manner. This condition of branching, as pointed out by 

 Allman, is common in the Sertularians, but rare among the 

 gymnoblastic hydroids. The hydranths are carried at the 

 summits of the main stem and primary branches, and are also 

 carried on secondary branches or ramuli, which are regularly 

 disposed along the distal border of the primary branches 

 (% 2). 



The number and arrangement of the polyps on the upright 

 stems approximate to the following plan : 



