454 Mr. II. J. Carter on Specimens 



others that I have found about the Melobesian nodules of the 

 Gulf of Manaar, beyond its larger size and sinuous form, it 

 being- a quarter of an inch long by l-24th inch in its greatest 

 transverse diameter. 



Hyclroid Zoophyte. 



Family Hydractiniidae, Hincks. 



Hydradendrium, n. gen. 



Gen. char. Polypary dendriform ; stem solid, with the excep- 

 tion of a small medullary canal, thickly spined. 



Hydradendrium spinosum, n. sp. 

 (PI. XIX. fig. 8, a-g.) 



Polypary dendriform, slender ; stem erect, branched ; 

 branches alternate, about l-24th inch apart, irregular in length 

 and disposition around the stem, extending upwards and out- 

 wards from the fixed to the free end, becoming shorter towards 

 the latter ; sometimes subdivided, but generally giving off on 

 each side a regular series of branchlets, arranged alternately 

 and plumosely, from which again spring sparsely a third set, 

 chiefly on one side. Consistence horny. Colour dark amber, 

 translucent (PL XIX. fig. 8). Stem and branches smooth, 

 except where interrupted by the presence of spines ; the latter 

 also smooth and directed upwards and outwards, in longitu- 

 dinal lines, wherein they are arranged alternately in adjoining- 

 rows, the rows increasing in number with the size of the 

 stem ; spine round, conical, slightly curved upwards, varying 

 in size from a slight indication at the growing ends of the 

 branches respectively to l-200th inch in length where fully 

 developed (fig. 8, b~f). Stem solid, with the exception of 

 an axial canal which traverses continuously every part of the 

 structure, and contains the sarcode upon which the whole has 

 been developed ; hence at the extremities of the branches the 

 latter is thicker in proportion to the horny material than at any 

 other part (fig. 8, c, d), composed of concentric layers through 

 which branches radiate from the axial canal to the branches 

 themselves and to the spines respectively (fig. 8, c), termi- 

 nating in the latter a little distance from the point, which is 

 therefore imperforate and itself formed by concentric layers 

 on the branch of sarcode first emanating from the medullary 

 or axial canal (fig. 8, e). Diameter of largest fragment of 

 stem found l-90th inch, that of the axial canal in the same 

 l-600th inch. Coenosarc covering the surface of the skeleton, 

 but not now elementarily distinguishable, on account of the 

 specimen having been dried. Spine often bifid, but where 



