7. Anthozoa (incl. Hydrocorallia). B. Alcyonaria. 29 



belemnon and Sclerobelemnon which have large polyps, but Mesobelemnon, which 

 occurs in shallow-water, has, nevertheless, large polyps. Fimiculina is inter- 

 mediate in build between the shallow and deep-water genera; specimens from 

 great depths are small, those from shallow water are several times larger; 

 therefore F. is an inhabitant of the littoral which has penetrated into deep 

 water. Balss' view [see Bericht f. 1910 Coel. p 40] that the absence of axis 

 is correlated with life in shallow and agitated water, does not explain the ab- 

 sence of axis in Echinoptilidse, which occur not only in littoral but in deep 

 waters. Diagnoses of the families and genera are given, and the following 

 are described Cavernulina n. (Veretillidse) 1, Veretillum 1, Cavernularia 8 (2n.), 

 Echinoptilum 1, Actinoptilum 1, Renilla 4, Sclerobelemnon 1, Kophobel. 3, 

 Anthoptilum (only one sp. is recognised) 1, Funiculina 2, ProtoptiJum 1, Sta- 

 chyptilum 1, Scleroptilum 1, Chunella 2 (1 n.), Amphiacme 1, Umbellula 8, 

 Pavonaria 1, Scytalium 2, Stylatula 3, Virgularia 9, Pennatula 9 (1 n. var.), 

 Leioptilum 2, Pteroeides 13, Struthiopteron 1, Sarcoplujllum 1. The geogra- 

 phical distribution of all species of Pennatulids is given in tabular form. 

 The numerous records from the coast of India indicate that here the develop- 

 ment of the Pennatulid stock probably took place; as also does the occurrence 

 of Lituaria, regarded as the most primitive genus, only in the warm portion 

 of this region. The Mediterranean appears to have acquired its Pennatulid 

 fauna from the Atlantic rather than from the Indian region; only one of the 

 7 Mediterranean species is endemic. Comparison of Arctic and Antarctic spe- 

 cimens shows that bipolarity does not occur in any species. The extraordinary 

 range in depth of some species (Koph. stelliferum, 36-3600 m.) shows that 

 they are independent of water-pressure. The distribution of each family is 

 discussed, and it is pointed out that, as a rule, the greater the depth at which 

 a species occurs the greater is its area of distribution. The internal struc- 

 ture of several genera is described. Cavernularia. In pusilla there are 4 canals 

 in the stalk, but no external openings were recognisable (in elegans and obesa 

 external apertures of the dorsal and ventral canals were found). The septa 

 between the canals are perforate, so that these communicate with each other 

 and also with the peripheral network of canals. Where the stalk merges into 

 the Kiel (the region which bears not only polyps but zooids; the term rachis 

 is not used in this memoir) a horizontal diaphragm is present, and is well 

 developed in 3 of the canals, but is almost absent in the fourth. Above this 

 partition the canals are narrowed considerably. On the walls of the principal 

 canals are numerous small canals, which lead into the ccelentera of the polyps; 

 the latter are also connected directly with the principal canals. One of the 

 median canals extends almost to the tip of the colony, but definite connection 

 with a polyp could not be established. In elegans the 4 canals can be followed 

 up the stalk to the beginning of the Kiel< , and then apparently cease suddenly, 

 there being a transverse diaphragm across each; but in the inner angle of each 

 diaphragm, near the axis, there is a small opening, which connects the canal 

 in the stalk with its continuation in the Kiel. The diaphragm is provided 

 with circular muscles, and doubtless acts as a strong sphincter. Above the 

 diaphragm the principal canals are much reduced, and are not recognisable in 

 the upper part of the colony. The axis has also disappeared in this region. 

 The canal system of obcsa agrees essentially with that of elegans. In two 

 series of sections of the former, one of the median canals was traced to the 

 upper end of the Kiel, and into connection with the coslenteron of a polyp. 

 The septa between the principal canals contain longitudinal spaces (intra-septal 

 spaces ) lined by endoderm. These are well developed in pusilla. In p. a. 



(T* 



