REPOET ON THE ALCYONARIA. 267 



The large specimen in the Jardin des Plantes exhibits a simple straight upright main 

 stem, which is much broadened below. It measures 150 mm. in height, and in diameter 

 5 mm. On the four sides it gives oflf, at tolerably wide intervals, thin cylindrical axial 

 polyps of the second order. These either bear small lateral twigs, especially about the 

 middle, or are directly beset with polyps. The latter arise at obtuse or at right angles. 



The largest of the specimens, collected by Dr. C. Keller near Nossi Be, is represented 

 in PI. XLIII. fig. 1, from a drawing kindly placed at our disposal by Dr. Keller. It 

 exhibits a somewhat divergent habit. 



The axial polyp of the first order attains a height of 170 mm., and measures 6 mm. 

 in diameter near the base ; at a height of 22 mm. it gives ofi" a strong branch, which 

 arises at an angle of 45°, and is beset with polyp-bearing axial polyps of the second 

 order. From that point the stem-polyp is continued upwards in a somewhat spiral 

 course, and gives ofi" its pol}'p-bearing twigs high above the origin of the first branch. 

 The twigs are strongest and longest about the middle ; above and below they are 

 less strongly developed, while just under the apex isolated polyps occur. Other 

 specimens, measuring 130 mm. in height and 4 mm. in thickness above the base, 

 exhibit only one stem with branches disposed on either side. At the middle height 

 these measure about 47 mm. in length and 15 mm. in thickness, and are directly beset 

 with polyps. 



In all the specimens the branches show a tendency to broaden out especially in one 

 plane, but an accurate examination of their origin shows that they arise, like the polyps, 

 in spirals round the stem. 



According to Dr. Keller the colonies attain a height of 200 mm. 



Axial stem-polyp of the first order. The axial stem-polyp exhibits at its upper end 

 the crown of tentacles. This surrounds the oral disc, and in all the specimens the tentacles 

 lie folded together over the invaginated oral disc. Each tentacle is looped or curved, 

 with its apex inwards. The mouth is a longitudinal cleft, surrounded by broad ecto- 

 dermic projections ; it measures 0'21 mm. in length. 



The tentacles seem to be short and broad, and have eight short side pinnae. 



The mouth leads into the oesophageal cavity, which seems on cross section to be oval, 

 and attains a length of 1'7 mm. No siphonoglyphe was foimd,^ but the tube is covered 

 with a layer of elongated cylindrical cells. After a course of 1 mm. the tube suddenly 

 contracts into a narrow cylindrical sack with thick walls, which leave only a narrow 

 opening. The latter opens into the gastral cavity. This is lined in its oesophageal 

 region by an endoderm of elongated cylindrical cells, which become less conspicuous 

 inferiorly, and more and more flattened. The mesenteric folds exhibit a very slightly 

 developed musculature, indeed muscular fibres are scarcely distinguishable. Under the 

 oesophageal tube they soon decrease in breadth and rapidly disappear below ; only the 



' A siphonoglyphe was found by Hickson, loc. cit., p. 695, pi. 50, fig. 3. 



