1886.] Zoological Observations made in North Celebes. 323 



men of it in sea- water, I examined it carefully at my house, and the 

 next morning I procured some more, and treated it in various ways 

 for microscopic examination. 



There are one or two features in the anatomy of this Alcyonarian 

 which throw a good deal of light not only upon the zoological position 

 of Tubipora but also that of the extinct Syringopora. 



At present I have only found this form on the inside of the reef 

 growing upon old and dead coral masses ; in its neighbourhood are 

 numerous specimens of Tubipora, some of them with unusually large 

 tubes, two or three species of Cornularia, a few Madreporas, and one 

 or two Astraeids. It clings to the rocks by a stolon of tubes, which 

 run in various directions and follow all the unevennesses of the sup- 

 porting rock. It is very easy, however, to pull it away bodily, without 

 injuring the stolon. 



The polype tubes spring perpendicularly from the stolon, and rise 

 to a height of 2 or 3 inches. I have not found any tubes longer than 

 that at present, in fact the average is rather below that. It may be, 

 however, as is the case with Tubipora, that the masses grow much 

 larger and the tubes much longer in more favourable localities. 

 The tubes are united together, not by platforms, as in Tubipora, 

 but by simple tubes, as in Syringopora (fig. 1), and from these con- 

 necting tubes new polype tubes spring. Each polype tube is marked 

 by eight grooves, corresponding with the eight mesenteries, and these 

 grooves, instead of running straight from the stolon to the mouth, 

 turn to the left, and run up the tubes spirally, plainly showing that 

 in the course of the growth of the polype from the stolon or connect- 

 ing tube it is twisted from left to right. Examining a portion of the 

 dried skeleton, I found that it is not purely calcareous, as is the 

 skeleton of Tubipora, but consists of a few long spicules imbedded 

 in a coriaceous substance, which is unaffected by strong hydrochloric 

 acid. I should not like to say for certain of what chemical nature 

 this substance is, but from its microscopic appearance I should expect 

 elastin. The tubes are not perforated as in Tubipora, and I cannot at 

 present discover any organic connexion between the mesoderm outside 

 the tube and the mesoderm inside the tube. 



The polypes very closely resemble the polypes of Tubipora. They 

 are of a rich brown colour, and contract but slowly when irritated. 

 The tentacles have the usual Alcyonarian character, and are richly 

 armed with nematocysts. 



At this season of the year this Alcyonarian does not seem to breed 

 at all, as after examining a great many polypes I have found none 

 sexually mature. The young colonies, which are to be found in abun- 

 dance on the reefs, closely resemble a species of Cornularia, which is 

 found here in abundance, consisting simply of branched stolons, from 

 which the young polypes spring. 



