306 CEYLON PEARL OYSTER REPORT. 



Lophogorgia lutkeni, WRIGHT and STUDER. Plate III., fig. 6. 



This species is represented by many pieces of colonies ; the largest piece measures 

 33 ceutims. in height by 38 centims. in breadth, and has three main branches. It 

 measures 18 millims. across at the base, narrows to 12 millims., and expands again to 

 28 millims. where the branches arise. The axis is dark brown in colour with a 

 lighter coloured central core. It is very calcareous as well as horny and measures 

 fully 2 millims. at the lower end of the branch which we studied. It has two 

 shallow grooves which correspond to the two grooves on the stem and the branches. 

 The branching is usually confined to one plane and is fairly profuse. In the 

 largest specimen one of the branches comes off from the main stem almost at 

 right angles to the plane ot branching, but it bends over almost directly and 

 comes to lie in that plane. In this specimen, also, several of the secondary 

 branches rise in a similar manner to the above. In the other specimens, however, 

 the branching is strictly confined to one plane. The stem and the branches are 

 flattened in the plane of branching and are marked on the flat sides by a narrow 

 winding groove or furrow which is continued along the flattened surfaces of the 

 secondary branches. The tips of the branches and twigs are almost cylindrical. In 

 the twigs the nutrient canals occur all round, but in the larger branches and in the 

 stem they correspond to the grooves on the flattened surfaces. 



The polyp-bearing surface is divided into two lateral bands by means of the two 

 grooves. On both of the bands the polyps occur in irregular rows. Verrucoe can 

 scarcely be said to be present, as the general coenenchyma seems only to be slightly 

 raised at the point where the polyp issues. On the polyp being retracted, the edge of 

 the pore-like opening curves in and forms a star-shaped figure in which the rays are 

 slightly variable. The slight thickening at the point of issue of the polyp seems more 

 marked in some of the specimens than in others. 



The polyps are either completely or partially withdrawn into the general 

 ccenenchyma ; the expanded part in the case of those partially withdrawn is white 

 in colour. On the body of the polyp there are eight bands of spicules running up 

 towards the base of the retracted tentacles. In each band the spicules, which are 

 numerous, are arranged en chevron. 



The spicules are spindle-shaped, but slightly flat in appearance, and sometimes 

 curved and with fairly large prominent projections. They measure (in situ) from 

 018 inillim. to 0'2 millim. in length. They are colourless. 



The general coanenchyma of the stem and the branches is thick, measuring about 

 1 millim. in depth, and friable in texture. In colour it is yellowish, with darker 

 brownish patches scattered over the whole surface. It is composed of short spindle- 

 shaped spicules with rough wart-like projections arranged in whorls, the whorls 

 varying in number with the size of the spicules. 



They measure, length by breadth in millimetres, as follows : O'l X 0'04 ; 

 0-12 X 0-04 ; 0-14 X 0'05 ; 0'14 X 0'02 : 0'13 X 0'035 ; 0'14 X O'OG. 



