92 htfrodudton to Animal Morphology. 



6. Bimeridse — hydrocaulus with a perisarc, or rudimental r 

 hydranths without an abruptly differentiated hypostome ;. 

 tentacles filiform, in a whorl around the base of the mouth \ 

 sporosacs fixed, ex. Bimeria. 7. BougainvillidcC — hydro- 

 caulus with a perisarc ; hydranths as last ; tentacles filiform 

 in a single circlet around the base of the hypostome ; gono- 

 phores phanerocodonic, with four radial canals ; marginal 

 tentacles simple or clustered, ex, Bougainvillea. 8. Euden- 

 dridse — hydrocaulus as last ; hydranths with an abruptly dif- 

 ferentiated peristome, and one circlet of simple verticillate 

 tentacles; sporosacs fixed, ex. Eudendrium. 9. Hydractinidse — 

 hydrophyton forming a continuous expansion, its deeper 

 part being a series of freely communicating tubes ofcoenosarc^ 

 covered by a chitinous perisarc ; hydranths, with filiform ver- 

 ticillate tentacles ; sporosacs fixed. In the female sporosacs, 

 there is a rudimental ectodermal male invagination, and in 

 the male sporosacs, the endoderm forms rudimental and 

 aborted ova, ex. Hydractinia. 10. Podocorynidse — hydro- 

 phyton an adherent expansion of adnate, inosculating tubes, 

 v/ith a chitinous perisarc ; gonophores phanerocodonic, ex. 

 Podocoryne. 1 1 . Cladonemidce — hydrocaulus developed, in- 

 vested by a perisarc ; hydranths with two kinds of tentacles, 

 filiform and capitate ; the phanerocodonic gonophores have 

 more than four radial canals, and branched marginal ten- 

 tacles, ex. Cladonema. 12. Nemopsidse — hydranths with a 

 proximal and distal circlet of filiform tentacles ; planoblasts 

 often blastochemes, with four canals, and clustered dissimilar 

 marginal tentacles, ex. Nemopsis. 13. Pennariadae — hydro- 

 caulus developed or none; hydranths with filiform and capitate 

 tentacles ; planoblasts with four canals and 1-4 marginal ten- 

 tacles, ex. Pennaria. 14. Cladocorynidae — hydranths with both 

 simple and branched capitate tentacles ; gonosome unknown^ 

 ex. Cladocoryne. 15. Myriothelidse — hydranth solitary; 

 hydrocaulus none; tentacles scattered, capitate; sporosacs on 

 processes from the body of the hydranth, ex. Arum. 16. Cla- 

 vatellidae — hydranths with simple, verticillate, capitate ten- 

 tacles ; gonophores are ambulatory medusae, with undeveloped 

 umbrella, and branching marginal tentacles, ex. Clavatella.. 

 17. Corymorphidae — solitary; hydrocaulus with no perisarc ; 



