in d. Naturgesch. d. nied. Thiere währ. d. Jahre 1872—1875. 445 



Farn. Clavatellidae. Hydranths with simple verticillate ca- 

 pitate tentacles. Gonophores in the form of ambulatory medusae 

 with undeveloped umbrella and branching- marginal tentacles. 



Clavatella Hincks (= Eleutheria Krohn). Hydrocaulus rudimental, 

 springing from a creeping filiform hydrorhrza, the whole invested 

 with a chitinous perisarc. Hydranth elongated with its tentacles in 

 a Single verticil, wbich siirrounds the base of a conical hypostome. 

 Gonophores developed in Clusters on branched peduncles from the 

 body of the hydranth. Rudimental umbrella not fitted for natation. 

 Manubrium short, conical, destitute of oral appendages ; radiating 

 canals six; marginal tentacles six, bifurcatcd, the outer brauch of 

 the bifurcation terminated by a capitulum of large thread-cells, the 

 inner by a claviform enlargement, wbich carries a suctorial disk of 

 attachment; on ocellus at the root of each tentacle, but no distinct 

 marginal bulbs. 



Gl. prolifera Hincks. 



Fam. Corymorphidae. Hydrocaulus solitary, destitute of 

 perisarc. Hydranth with a proximal and a distal set of filiform ten- 

 tacles. Gonophores in the form of medusiform planoblasts with four 

 radiating canals and one or more simple marginal tentacles. 



Corymorpha Sars (p. p.). Hydrocaulus emitting towards its 

 proximal extremity tubulär fleshy processes; perisarc replaced by a 

 delicate filmy pellicle. Hydranths flask-shaped, abruptly distinct 

 from the hydrocaulus; poximal tentacles imperfectly contractile, lar- 

 ger them the distal, and arranged in a single verticil near the base 

 of the hydranth, the distal tentacles very contractile, forming several 

 closely approximate alternating verticils round the base of a conical 

 hypostome. Planoblasts borne on branched peduncles which spring 

 from the body of the hydranth between the proximal and distal 

 set of tentacles, with a deep-belled umbrella, a well-developed simple- 

 mouthed manubrium and a single marginal tentacle; each of the 

 radiating canals terminates at the junction with the circular canal 

 in a bulbous expausion without distinct ocellus; one of these bulbs 

 is larger than the other, and from this ^alone the solitary tentacle 

 is developed. 



C. nutans Sars. 



Halatractus n.gen. Hydrocaulus surrounded towards its proxi- 

 mal extremity with tubulär fleshy processes. Hydranth abruptly 

 distinct from the hydrocaulus; the proximal set of tentacles in a 

 Single verticil, and larger than the distal, which are scattered or 

 subverticillate round the base of a conical hypostome. Planoblasts 

 sessile, springing from the body of the hydranth between the pro- 

 ximal and distal sets of tentacles; umbrella at the time of libera- 

 tion bell-shaped, with one of the four radiating canals continued 



