CORYN1D&. 123 



age, they present a central stomach, with four canals in the form of a 

 cross, and four to eight tentacles with cirri. The Corynidce compre- 

 hends many genera ; among others the genera Coryne, Hydr actinia^ 

 Tubularia, and Cordylophora^ in studying which Van Beneden of 

 Louvain discovered most interesting facts connected with the subject 

 of alternate generation. 



The Hydrozoa forming the Corynidse have the power of secreting 

 a hollow tube of a horny nature, in which the fleshy body can move 

 up and down, expanding its tentacles over the top. Others of them 

 give forth buds, each of which takes the form of a polyp, and these, 

 being permanent, give it a shrub-like or branched appearance ; it is 

 now a compound polyp. The tube is branched, but the orifices from 

 which the polyps expand never dilate into cups or cells. The Tubu- 

 laria are plant-like and horny, rooted by fibres, tubular, and filled 

 with a semi-fluid organic pulp ; polyps naked and fleshy, protruding 

 from the extremity of every branchlet of the tube, and armed with 

 one or two circles of smooth filiform tentacles ; the reproductive 

 bodies germinating from the base of the tentacles ; embryo medusi- 

 form. "Some modern authors," says Fredol, "assure us that the 

 tree-like form of these polyps is a degraded and transitory form of 

 the Medusae. The Medusa originates the polyp, the polyp becomes a 

 Medusa." Eudendrium rameum so perfectly resembles an old tree in 

 miniature, deprived of its leaves, that it is difficult to believe it is 

 not of a vegetable origin ; it is like a vigorous tree in miniature, in 

 full flower, rising from the summit of a brown-spotted stem, with 

 many branches and tufted shoots, terminating in so many hydra-like 

 polyps of a beautiful yellow or brilliant red. E. ramosum, of a 

 brownish colour and horny substance, rising six inches, is rooted by 

 tortuous, wrinkled fibres, with flexible, smooth, and thread-like shoots, 

 branching into a doubly pinnate form. In Tubularia indivisa the 

 tubes are clustering ; its numerous stems are horny, yellow, and from 

 six to twelve inches in height, about a line in diameter, and marked 

 with unequal knots from space to space, like the stalk of the oat-straw 

 with the joints cut off. Their lower extremity is tortuous, attaching 

 themselves readily to shells and stones in deep water, flourishing in 

 deep muddy bottoms, and upright as a flower, fixed by the tapering 

 root-like terminations of their horny tube : a flowering animal, having, 

 however, neither flower nor branch. At the summit of each stem a 

 double scarlet corolla is developed of from five to thirty-five petals, 

 in rows, the external one spreading, those in the interior rising in 

 a tuft ; a little below, the ovarium appears, drooping, when ripe, 

 like a bunch of orange-coloured grapes. After a time the petals 



