STAURIDIUM PRODUCTUM. 371 



The filiform tentacles arc less contractile and somewhat more rigid than is usually the case 

 with the tentacles of the Hydroida. This character they possess in common with the similarly 

 formed tentacles in the hydranth of Chuhnema. Hincks names them " false tentacles," but their 

 structure docs not essentially differ from that of the filiform tentacles of most other marine 

 hydroids. 



Stauridium peoductum, Wr'ujht. 



Plate XVII, figs. 11 and 12. 



Stauridia producta, — Sirethill Wright, in Proc. Roy. Phys. Soc. of Edin. for April, 1857, 



pi. xix, figs. 7 — 9. 

 Stauridium PRODUCTUM, — Hhicks, Brit. Hydr. Zooph., p. 58, pi. xii, fig. 1. 



TROPHOSOME. — IIxDiioPHYXON attaining a heiglit of about a quarter of an 

 inch ; HTDEOCAULUs Simple, or with a few irregularly disposed branches, shorter than 

 the hydranth, and springing at intervals from a creeping filiform htdrouhiza. 

 HroEANTHS cylindrical, the capitate tentacles in three verticils, the filiform tentacles 

 tapering to a blunt point. 



GONOSOME. — GoNOPiiORES developed at " the base of the lower capitate 

 tentacles ;" umbrella of medusa set with scattered thread-cells, marginal tentacles with 

 the terminal cluster of thread-cells larger than the others. 



Colour. — Hydranth white, perisarc pale yellowish-brown ; manubrium and marginal bulbs 

 of medusa rose coloured. 



Development of Gonosome. — Summer. 



Habitat. — Rock pools. 



Batliymetrical distribution. — Literal zone. 



Localities. — Firth of Forth, Dr. S. Wright ; Ilfracombe, Rev. T. Hincks ; Penzance, 

 G. J. A. 



This elegant little hydroid is rendered very remarkable by the symmetrical disposition of 

 its tentacles in crucial verticils, situated at nearly equal distances from one another along the 

 cyhndrical body of the hydranth. I met with it at Penzance during the autumn in considerable 

 abundance, attached to the bottom of shallow rock pools, a little above low-water mark, but 

 neither my specimens nor those originally described by Dr. Wright carried gonophores, while 



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