7. Anthozoa (incl. Hydrocorallia). B. Alcyonaria. 33 



such horny cords. There is a very distinct axis-epitheliuin, which does not 

 differ in structure from the rest of the eudoderm. The authors agree with 

 Jungersen that the apex of the colony undergoes degenerative changes. This 

 view is further supported by the fact that the upper full-grown polyps are sterile, 

 and only the lower younger ones bear gonads. (In affinis the upper polyps 

 also bear gonads; this is the case also in Stylatula and in Koph. stellif.) The 

 parietal longitudinal muscles are wanting, but there is a more centrally situated 

 longitudinal musculature. - There are also observations on the structure of 

 Pennatula and Ptcroeides. In general, in those Pennatulids in which the polyps 

 and zooids are arranged all round the Kiel, the 4 principal canals are about 

 equally wide and reach to the lower end of the stalk, while in those the 

 polyps of which exhibit a well-marked lateral arrangement the lateral canals 

 extend to a varying distance down the stalk, but not to its end. These canals 

 are shortest in Renilla, being restricted to the >Kiel. The musculature of the 

 stalk, which is much stronger than that of the Kiel, can not be relied upon 

 as an index of affinity, for it has varied forms in nearly related species. It 

 may be assumed that in all Pennatulids the axis arises from endodermal cell- 

 cords (situated in the mesogloea) and from connective tissue fibres. The 

 authors discuss the phylogeny of Pennatulids, and conclude that they arose 

 from Alcyonacea, probably from some genus not far removed from the Telestidse. 

 They also discuss the inter-relationships of the members of the order Penna- 

 tulacea, for an account of which see Bericht f. 1910 Coel. p 39. 



Niedermeyer opens his account of Pteroeides griseum by describing the ex- 

 ternal features and the terminology which he applies to the various portions 

 of the colony. The variation in size and in the proportions of the parts of 

 adult specimens is due to the varying amount of contraction of the specimens. 

 In an adult colony there are about 35000 individuals. The colours of living 

 specimens are described. P. spinosum is only a var. of griseum (Kolliker's 

 var. longispinosum}', there are no anatomical differences between them. In 

 Pennatula and Pt. the dorsal and ventral canals of the stalk open separately 

 to the exterior at the lower end, each by a single pore, and other openings 

 are not present. The additional pores described by Musgrave [see Bericht 

 f. 1909 Coel. p 55] were probably ruptures produced by pressure during in- 

 jection. The hook-like lower end of the axis lies generally in the ventral 

 canal of the stalk; Musgrave's suggestion that the curvature of this end of the 

 axis is due to contraction of the colony is correct. Consideration of the struc- 

 ture of the axis leads the author to support Studer's theory of axis-origin, 

 although an axis-epithelium is present. The arrangement of the muscles in the 

 stem is closely correlated with that of the canal-system. The mesoglceal 

 lamellae, on which the muscle-fibres are situated, are strongly folded in a 

 characteristic manner. An endodermic musculature is present at the base of 

 the epithelium lining the principal canals, and serves to diminish the diameter 

 of these canals. The polyps, and the zooids of the pinna? and of the rachis 

 have a definite orientation. Each tentacle of a polyp has 13 or 14 paired 

 pinnules and one unpaired. The oral disc often appears dark owing to the 

 aggregation of brown, granular endodermic gland-cells, which often have a de- 

 finite arrangement. A siphonoglyph is not present in the polyps. The zooids 

 of the pinna? are very small papilhc, without tentacles and mesenterial filaments; 

 almost the whole circumference of the stomodaeum is occupied by the siphono- 

 glyph. The stomodseum is always bent towards the dorsal side. Spicules and 

 nematocysts do not exist in these zooids. The mesenteries are very short, 

 being present only in the distal portion of the zooid, and muscles are absent. 



