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NATURAL HISTORY. 



I'ODOCOKYNE CAHNEA. (After Oilman.) 



The buds on the generative tentacle-bearing parts develop into medusae, which are deep bell-shaped. 

 Each has the outer surface dotted with scattered thread cells, and there is a velum or membrane 

 between i;he margins of the bell with a central opening. There are from four to eight marginal 

 tentacles with bulbous bases destitute of ocelli. Four radiating canals are to be seen, and the mouth 

 or manubrium is small and four-lipped. 



Other Tubularians belonging to the family Clavidse may be instanced by a veiy pretty species* 



belonging to the genus Syncoryne,t which is 

 characterised by having numerous club-shaped 

 hydranths united in a common colony. The 

 tentacles, moreover, are scattered on the clubs 

 and are not in whorls, and the gonophores are in 

 the form of medusae, with four radiating canals 

 and four marginal tentacles. The little species is 

 of a deep orange colour, and this tint is found 

 on the medusa buds as well as on the hydranths. 

 The little colony is about half an inch in height, 

 and the trophosome has its tentacles knobbed and 

 along the length of the club-shaped part. The 

 medusa buds (gonophores) are in short peduncles, 

 just below the tentacles. These are developed in 

 April, and when the medusa is ready to escape it 

 has four very extensible tentacles at the margin of 

 the timbrel la, and is nodulated with clusters of 

 nematocysts. A distinct ocellus is on the base of 

 each tentacle. It is, of course, not covered with a 

 membrane, and is "naked-eyed." The mouth is 



short, and there is a membrane or velum extending across the opening of the manubrium with a 

 central opening in it. 



Allman found a branching Hydroid in fresh water, and it has since been proved to live in lakes, 

 docks, and rivers in Great Britain generally. It seeks the shade, and is found under logs of 

 wood and attached to the sides of dark cisterns. The whole colony may be one inch and 

 a half to three inches long, but the hydranths continually contract and enlarge, and are very 

 changeable in shape. It is called Cordylophora lacustris. 



The gonophores which produce the young on the stem are long and oval in shape, and these 

 escape from them, not in the form of medusae, but as long ciliated bodies or planulse. The planula or 

 embryo settles down, loses its cilia, and becomes a stem and hydranth. 



The last family to be noticed contains a very large and common species belonging to the genus 

 Tubularia.+ The characters of the family are that the hydranth has two whorls of tentacles, one in 

 front of the other. There is a chitinous investment, like a tube, to the root-stem, and the gonophores 

 are in the form of fixed sporosacs, in clusters, reaching clown like branches of currants, below the 

 crown of tentacles. These are seen in all stages of growth, and the large ones are the lowest. A zooid 

 escapes from each in the shape of a cylindrical stem with a stellate root and a crown of tentacles, 

 and it grows into a hydrosome. The calycles of the mature form are apt to bend down ; one drops 

 off and a new one starts from the wound. 



They are very beautiful objects, and the cylindrical sterns rise without a branch to the height of 

 sevei'al inches, and the tentacular head is scarlet or crimson in colour. Its longer tentacles spread 

 out and retract, and the gonophores droop gracefully amongst them. Spring and summer are the 

 times when this species of the Atlantic and British seas is in perfection, and it is during its most 

 active growth that the tentaculate heads are cast off and renewed. 



SUB-ORDER CAMPANULARIA. 



The sub-order of Hydroids, which are not only furnished with a chitinous investment over 

 * Syncoryne pulchella. t Greek, syn, together with ; korytie, a club. J Tubularia indivisa. 



