CLADONEMA RADIATUM. 63 



tentacles placed a little above the termination of the 

 body and at right angles to it, rounded at the tip ; 

 GONOPHORES large, two or three in number, developed 

 at the base of the inferior tentacles. 



GONOZOOID. UMBRELLA deep bell-shaped, covered with 

 minute thread-cells, slightly produced and pointed at 

 the top, immediately over the base of the manubrium ; 

 MANUBRIUM fusiform, lobed, with 5-7 oral tubercles ; 

 MARGINAL TENTACLES springing from red bulbs, each 

 with a dark ocellus, more or less branched, very exten- 

 sile, roughened by prominent groups of thread-cells, 

 and furnished with a variable number (1-4) of filiform 

 appendages, terminating in suctorial disks. 



DUJARDIN was the first to describe this very curious and 

 beautiful Hydroid. He has given a full account, accom- 

 panied by admirable figures, of its structure and develop- 

 ment. It has also been studied by Krohu, Gegenbaur, 

 and Van Benedeu. Gosse has described the polypites 

 from Devonshire specimens, but did not meet with the 

 reproductive bodies. 



My friend Mr. E. W. H. Holdsworth has been fortunate 

 enough to procure several specimens of the free zooid from 

 the tanks in the Zoological Gardens, and has succeeded 

 in keeping them, so as to trace almost the entire course 

 of the reproductive history, while his own aquarium has 

 yielded the polypites in considerable numbers. His notes 

 and sketches he has very kindly placed at my disposal ; 

 and they enable me to supply an original account of the 

 species, which corroborates, and in one or two points 

 corrects, that which we have from Dujardm. 



The polypites are very mutable in form, as the accom- 

 panying woodcuts, which are careful studies from nature, 

 will show (fig. 5). Fig. /represents an individual that has 

 swallowed a Cyclops, whose tail protrudes from the mouth. 



