34: Coelenterata. 



The zooids of the rachis differ from those of the pinna? in their greater size, 

 the presence of a calyx-like structure, the more complete development of their 

 mesenteries, which possess muscles, the feebler siphonoglyph, the straighter 

 course of the stomodseum, the presence of spicules and nematocysts, and the 

 greater amount of their gland-cells. There are therefore 3 different kinds of 

 individuals in the colony. The zooids of the pinnae are more primitive (for 

 they agree in structure with the youngest polyp-buds), those of the rachis (which 

 are in many points similar to the adult polyps) secondary. The canals con- 

 necting the polyps and zooids, and the growth of the pinnae are described. 

 Ectodermic gland (mucous) cells occur chiefly in the polyps and zooids, and 

 are the seat of light-production. In the stalk there are numerous ectodermic 

 gland-complexes, forming papillae with two kinds of gland-cells mucous and 

 granular (albumen) - - which appear to form the bright orange-red colour of 

 the stalk. The nervous system was studied by means of macerations and 

 methylene blue. The latter method revealed, in the coenenchyme, a plexus, 

 which appears to belong to a colonial nervous system. The endoderm is 

 rich in gland-cells, which have granular dark-brown contents, and to these the 

 dark colours of the colony are due. Fat was found in the endoderm. The 

 capillare ErnahrungsgefaCe (Kolliker), which run in the mesogloea, open on 

 the external surface of the colony. The various forms of spicules are described. 

 During the day the colony is contracted and is buried in the sand, except the 

 upper third of the rachis, but at night it dilates and extends, and all the 

 rachis is above the sand. The peristaltic movements and the action of burrowing 

 (which takes place as in ScytaUopsis, see Bericht f. 1907 Coel. p 35) are de- 

 scribed. Free-swimming and active movement, which Musgrave regarded as 

 probable in this Pennatulid, do not occur. The production of light is 

 associated with the ectodermic gland-cells, and takes place only in the polyps 

 and zooids, which are luminescent after having been separated from the stem. 

 By day the light-emission is reduced; it is increased on supplying oxygen and 

 takes place on the application of mechanical, thermal, electrical and chemical 

 stimuli. 



G. Hydrocorallia. 

 See Gravier( 4 ), Parona & Crema & Prever and Ritchie ( 2 ). 



D. Incertae sedis. 



Parks (*) remarks that in some of his specimens of Stromatopom the radial 

 pillars are 24 to the mm. If this is the skeleton of a colony of zooids, each 

 individual must have been very slender, and such tenuity seems improbable in 

 the case of any Coslenterate. The genus ., as represented by the examples 

 referred to, is evidently nothing more than an extremely fine Actinostroma 

 pierced by numerous vertical tubes the so-called zooidal tubes. The author's 

 observations tend to turn him strongly away from Nicholson's conclusions as 

 to the Hydrozoan affinities of the Stromatoporoids. He describes Clathro- 

 diotyon 1, Syringostroma 5, Stromatopora 8 (3 n.), Actinostroma 3 (2 n. and 

 1 n. var.), Clathrodictyon 7 (1 n. var.), Actinodictyon n. g. (Actinostromidse) 4 n. 7 

 Aulocerium n. g. (near Labechia) 1 n. See also Bakalow, Osimo. Parks ( 2 ), 

 and Vinassa de Regny( 1 , 2 )- 



