7. Anthozoa (incl. Hydrocorallia). A. Zoantharia. 35 



structures, which the author has examined in 3 species of If., have nothing 

 to do with the mesenteries. They are modified tentacles and the ectodermic 

 canal represents a portion of the oral disc, converted by fusion of 2 neighbouring 

 tentacles into a tube, which has become enclosed in the body of the modified 

 polyp. Moreover the canals do not open into the pharynx but into a depressed 

 or invagiuated part of the oral disc. There is a constant relation between the 

 presence of these U-shaped canals in an individual and the apparent absence 

 of tentacles. Specimens were observed apparently without tentacles but with 

 6 of these canals. It is the dorsal (not the ventral) tentacle which becomes 

 modified in Seriatopora, Stylophora and Poscilopora (correction to Krempf, see 

 Bericht f. 1903 Coel. p 20). 



Marenzeller( 1 ) gives a list of stations from which stony corals were obtained 

 by the Valdivia, the depths at which they occurred and records and describes 

 Desmophyllum 1, Flabellum 1 (5 n.), Sphenotrochus 1 n., Deltocyathus 1, Caryo- 

 phyllia 5 (1 n.), Stenocyathus 1, Aulocyathus n. g. (a Turbinolid) 1 n., Cerato- 

 trochus 1 n., Stephanotrochus 2 n., Lophohelia 1, Amphihelia 1, Solenosmilia 1, 

 Parasmilia 1, Bathyactis 1, Balanophyllia 1, Dendrophyllia 1, Ccenopsarnmia 1, 

 Anisopsammia n. g. (a Dendrophylliid) 1 n. In describing Car. clavus he 

 remarks that the diagnoses of M. E. & H. and of Lacaze Duthiers require to 

 be supplemented. The breadth of the base of the coral varies with the nature 

 of the substratum, but if it fall below a certain minimum the calice falls over 

 with increasing weight. The influence of its altered position is especially 

 shown in the curvature of the calice due to the tendency to upward growth 

 of the part of the theca which lies on the bottom. The calice is at first 

 cylindrical, then goblet-like, but when older is compressed in the direction of 

 the shorter axis. It may be cylindro-conical with almost circular aperture. 

 The thin theca generally becomes thickened in free individuals. Septal teeth 

 and costse do not form constant characters: in individuals which have been 

 long fixed they attain a very high degree of development, in free forms they 

 may be merely indicated. The 5th cycle of septa may be complete but in 

 forms which lie upon the substratum the septal increase is limited. 



Yakovleff has examined Russian specimens of the Upper Palaeozoic coral 

 Lophophyllum proliferum. The primary septum on the concave side (the 

 counter septum in Russian specimens, the main septum in American ones) is 

 short, while that on the convex side is long. This may be due to the direc- 

 tion of the bend of the coral. The author defines the primary counter sep- 

 tum as that in relation to which (1) the contiguous septa are arranged in a 

 parallel direction and (2) the adjoining primary interseptal chambers contain 

 no new septa. 



Agassiz^ 1 ) gives a general sketch of the characteristics of the coral reef 

 groups of the Pacific and describes in detail the following groups. In the 

 Marquesas (as in the Galapagos) corals are limited to restricted shore areas, 

 they do not even form fringing reefs, but are mere patches in the shallow 

 protected bays. This is attributed to the fact that there have been no great 

 platforms of erosion formed at the base of the slopes of these islands so that 

 corals find a depth suitable for their growth only in the closest proximity to 

 land. This is confirmed by the conditions seen in the Galapagos and in the 

 island of Mehetia (S. E. of Tahiti) where the absence of a shore platform is 

 most striking, the more so as Mehetia is in a region where corals are well 

 developed upon the shore platforms of other volcanic islands. There are no 

 indications that subsidence has occurred either in the Galapagos, the Marque- 

 sas or in Mehetia. The Paumotu Archipelago consists of more than 



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