128 



Cionistes Wrght. Hydrophyton consisting of a retiform hydro- 

 rhiza without developed hydrocaulus. Hydranths sessile on the hy- 

 drorhiza, minute, with a single verticil of filiform tentacles. Sporo- 

 sacs borne by blastostyles, which spring from the hydrorhiza. 



C. reticulata Wrght. 



Fam. Bougainvillidae. Hydrocauhis more or less developed, 

 invested by a conspicnous perisarc. Hydrauths with the hypostome 

 not abruptly diflPerentiated; tentacles filiform, in a circlet round the 

 base of the hypostome. Gonophores phanerocodonic, with four simple 

 radiating canals, and with the marginal tentacles simple and distri- 

 buted either singly or in Clusters. 



Bougainvillia Less. Hydrophyton consisting of a branching 

 hydrocaulus, which is rooted by a filiform hydrorhiza. Hydranths 

 fusiform, with a conical hypostome. Planoblastes (= Hippocrene 

 Brdt., Margeiis Steenstr.) borne by the hydrocaulus and having at 

 the tirae of liberation a deep bell-shaped umbrella, with the manu- 

 brium shorter then the height of the bell-cavity and with four simple 

 labial tentacles, each of which carries at its extremity a little capi- 

 tulum of thread-cells; radiating canals, each terminating at itsjun- 

 ction with the circular canal in a bull), from w'hich two tentacles 

 are developed, each tentacle having an ocellus at its base. 



B. ramosa van Bened., B. fruticosa Allm., B. superciliaris Ag., 

 B. carolinensis McCr., B. muscus Allm. Unsicher: B. Mertensii A. 

 Ag. und Eudendrium pusillum Sars. 



Diplura n. gen. Hydrophyton solitary, rooted by a filiform 

 hydrorhiza, and surmounted by a claviform hydranth. Planoblasta 

 spi'inging from the body of the hydranth at the proximal side of ten- 

 tacles. Umbrella deep bell-shaped; manubrium with simple or qua- 

 driloliate niouth; radiating canals terminating each in a marginal 

 bulb, one of which, in the mature medusa, carries a pair of filiform 

 tentacles, the others being destitute of tentacles. ^ 



D. fritillaria Steenstr. 



Perigonimus Sars. Hydrophyton consisting of a branching or 

 simple hydrocaulus rooted by a filiform hydrorhiza. Hydranths fusi- 

 form, with a conical hypostome. Planoblasts developed from the 

 hydrophyton. Umbrella at the time of liberation, deep bell-shaped, 

 with the oral extremity of the manubrium either simple or more 

 or less deeply lobed; marginal tentacles either two or four, not in 

 Clusters, and with bulbous bases, which aro not furnished with di- 

 stinct ocelli. 



P. muscoides Sars, P. repens Wrght (= Eiid pusillum Wrght), 

 P. minutus Allm., P. sessilis Wrght, P. palliatus Wrght., P. vestitus 

 Allm., P. serpens Allm., P. linearis Alder. Zweifelhaft: Atractylis 

 bitentaculata und A. quadritentaculata Wrght. 



