i. Stylaster eximius Duchassaing and Michelotti 



& 



S. elegans Duchassaing and Michelotti. Les Coral. des Antillcs. Supplement p. 68, PI. IX. 



fig. 4. 1864. Name of species preoccupied, renamed as follows: 

 5". eximius Saville Kent. Proc. Zool. Soc. Lond. April 4'h 1871. 

 5. duchassaingii Pourtales. Deep-Sea Coral. 1871, p. 35, PI. VI, fig. 1 and 2. 43 fms, 



Tortugas. 



The greatest depth at which the specimens which are grouped round the species S. 

 eximius, in the Siboga collection, have been found is 118 M. (6$ l l 2 fms.). The least depth at 

 which, in this collection, an old or new distinct species has been found is 204 M. (S. óiloóatusj. 

 It is especially interesting to note that this species recorded at 204, 469 and 520 M. varies, 

 to not a small extent, with these localities and the specimen that comes from 204 M. is the 

 least specialised and most closely related to S. eximius. The large species 5. eximius has 

 been divided into a number of facies. 



a. 6. eximius fac. altus. Plate I, figs. 1 — 3. 



Stat. 164. i°42'.5 S., I30°47'.5 E. W. of New Guinea. 22 M. 2 pieces. 



Stat. 144. S. of Halmaheira. 45 M. Several small pieces. 



Stat. 282. S°25'.2S., I27°i8'.4E. E. of Timor. 27 — 54 M. or from reef. 1 fragment. 



Stat. 303. Between Timor and Samau lis. Up to 36 M. Several pieces. 



This is a tall, subflabellate coral with non-anastomosing branches (Fig. 1). The height 

 is about 100 mm., the diameter of the main stem at its base 3 mm., the axis at the base of 

 the terminal branches from 0,8 to 1 mm. The colour is white, but one branch among the 

 many pieces from Stat. 303, was faintly suffused with pink in certain regions, which included 

 some side branches, about the middle of its length. The surface of the hydrophytum, including 

 the ampullae is smooth, but fine longitudinal striations caused by rows of vertical canals of 

 the coenosarc can be seen under magnification on the younger branches. The bracket-like 

 cvclosystems (Fig. 2 — 3) are small, being from 0,7 to 0,8 mm. in transverse diameter and 

 projecting 0,4 mm. from the surface. Alternate cyclosystems, that is to say adjacent ones on 

 the same side of the stem, are about 1 — 6 mm. apart. 



The method of growth appears to be infiuenced considerably by the production of 

 ampullae. A great production of gonads seems to retard growth in length; the thickness of 

 the branches increases considerably; the cyclosystems seem to become relatively smaller and 

 less important, they project less, that is to say, are less bracket-like and are often joined 

 (cf. S. bellus). When this is the case, fresh dactylozooids may be formed so as to complete the 

 cycle (Fig. 3). Colonies are often found in a transition stage, but one old, dark-coloured 

 specimen from Stat. 282 has almost entirely complete cylosystems, with joined septa, and these 

 cyclosystems, in the older parts of the stem, lie flat on the surface and gradually become 

 quite overgrown by the coenenchym. On the younger branches the lovver, abaxial edge of 

 the cyclosystem projects slightly. 



The specimen drawn and described by Duchassaing and Michelotti probably belongs 



SIHOGA-EXPEDITIE VIII. 2 



