OF THE MERGUT ARCHIPELAGO. 



235 



about 12 inches in height, by about the same in its probable 

 original lateral extent ; it has about 80 or 90 terminal branches ; 

 the stem is about 1| inches high, and it gives off its next 

 branches in rapid succession. The second specimen is in spirit, and 

 from its size and slightly branched condition is pretty obviously 

 young ; it is 4^- inches high by about 1\ in greatest width, the 

 stem is 1^ inches long ; it gives off four branches alternately, and 

 ends in the middle of its branches in a cluster of Cirrhipede galls ; 

 the most branched of the axes to which it gives rise sends off 

 one horizontal shoot, from which arise at almost right angles three 

 secondary twigs, so that this rectangular mode of branching is 

 probably specific ; the stem and branches are approximately 

 cylindrical, the places of bifurcation being slightly flattened ; 

 the tips of the pinnae are slightly clavate ; colour in spirit dark 

 vermilion. 



This species is mainly characterized by its colour. 



Lamouroux, the first to distinguish the genus, says, in 1816 

 ('Hist. Polypiers Coralligenes flexibles,' p. 428), that the Plex- 

 auras show none of the light tints of the Gorgonias, so he could 

 not have known of this form. No similar species seems to have 

 been since described. 



There is some superficial resemblance between Plexaura indica 

 and Echinomuricea indomalaccejisis, Ridley (Rep. Zool. Coll. 

 H.M.S. ' Alert,' p. 336, see pi. xxxvi. figs. B, B), and Eclino- 

 gorgia pseudosappo, Kolliker (Icon. Histioi. p. 136), also from the 

 East Indies ; E. sasappo, Esper, is another scarlet species from 

 the East Indies. We very possibly have here some mimicry ; 

 the Echinomuricea, being well protected by its projecting 

 verruca-spicules, may perhaps be imitated by its smoother 

 companion. 



Judging from some well-executed drawings of spicules in the 

 collection of Dr. Ondaatje, and lent by him to the Museum, this 

 species appears to occur on the Ceylon coast. 



Psahmogorgia ? plexauroides, n. sp. (Plate XVII. figs. 1-6.) 



Corallum erect, ramose, typically flabelliform, of straggling 

 growth. Stem (in the single example) short, apparently typically 

 alternately pinnate, varied by unilateral pinnation in crowded 

 parts; branches given off at intervals of about ^ to 1 inch, at 

 about right angles, the angle tending to become acute towards 

 periphery of corallum ; terminal pinnae commonly about 6 inches 



