206 Dr. A. KorotiiefF on Polyparium ambulans. 



live and can hardly be orientated, A section made as above 

 described is shown in PL XIII. fig. 2. In this section it is seen 

 that the superior free surface of the colony is beset with clavi- 

 form buccal cones [Mh) ; these, as already stated, are quite 

 destitute of tentacles and have no septa ; they are hollow, 

 have a buccal aperture opening outwards [M. o), and another 

 inner orifice {M'. o') which leads into the interior of the body 

 of the colony. The inner space is rather complex and con- 

 tains various walls, the analogy of which with the ordinary 

 septa of corals is very doubtful at the first glance. The body 

 of Polyparium possesses a spacious cavity, which is divided 

 into sections of equal size by the above-mentioned septa. 

 These septa stand transversely to the long axis of the body 

 and in a vertical longitudinal section are shown as bands 

 (fig. 2). In this figure we see how the partition-walls (septa) 

 are united in pairs. Each pair forms a special division 

 which encloses an internal chamber (^/) and is separated 

 from the neighbouring one by an intermediate chamber [sf). 

 According to this description therefore the body of Poly- 

 parium presents a conglomeration of consecutive divisions or 

 segments, which, however, cannot be characterized as meta- 

 meres ; for each metamere is a definite unit, which forms a 

 particular part of the body, possesses only a single partition, 

 and is immediately applied against its like. In Polyparium 

 each segment is formed by two partitions, and is separated 

 from the neighbouring segment by an intermediate chamber. 

 The partitions stand in a particular relation to the buccal 

 cones on the one hand and to the acetabula of the sole on the 

 other (fig. 2) . Thus the interior chamber (bf) opens exter- 

 nally by means of the buccal aperture, but below, corre- 

 sponding to the buccal apertures, are the acetabula, which are 

 so distributed that each buccal cone possesses a corresponding 

 acetabulum. Hence w«e may perhaps regard each buccal cone 

 with its acetabulum as a simple individual, which, however, 

 has not yet sufficiently individualized itself. I must, how- 

 ever, remark that each acetabulum possesses a separate clavi- 

 form cavity ; this stands in direct connexion with the lumen 

 of the animal, and corresponds in position with the cavity of 

 a buccal cone. 



Before passing to the histology of Polyparium I may 

 premise that in this respect the creature exactly agrees with 

 the Actinise — not only the sequence of the layers, even the 

 intimate structure of the tissues is in both cases exactly alike, 

 and whoever has once seen a section from the wall of an 

 Actinia will at once recognize the same thing in Polyparium. 

 In accordance with the Actinian type the ectoderm, tlie ento- 



