TUBULARIAE 



97 



free-swimming medusa which is usually borne on the hydrocaulus and 

 has 4 radial canals; marginal tentacles either single or in clusters, and 

 4 or 8 manubrial gonads : about 19 genera. 



Key to the genera of Bougainvilliidae here described: 



&! Hydroid colony arborescent ; medusa with tentacles in clusters. 

 &! Medusa with tentacles in 4 clusters. 

 c x Medusa without short knobbed tentacles ; hydroid arborescent. 



1. BOUGAINVILLIA 



c 2 Medusa with a pair of short knobbed tentacles at each cluster. .5. NEMOPSIS 



& 2 Medusa with tentacles in 8 clusters ; hydroid like Bougainvillia . .4. RATHKEA 



o 2 Hydroid colony with creeping hydrorhiza ; medusa with only 2 long tentacles. 



& x Four short oral lobes 2. PERIGONIMUS 



& 2 Four long oral lobes 3. STOMOTOCA 



1. BOUGAINVILLIA Lesson. Trophosome : col- 

 ony arborescent with a dense perisarc, hydranth 

 with conical hypostome. Gonosome: medusa 

 globular, with branching oral tentacles and 4 

 pairs at first and later 4 groups of marginal 

 tentacles: 20 species. 



B. carolinensis (McCrady) (Fig. 156). Col- 

 ony may be 25 cm. high, usually 7 to 12 cm.; 

 hypostome conspicuous; tentacles about 12; 

 medusa with brick-red manu- 

 brium and black ocelli, 4 mm. 

 in diameter: Cape Cod and 

 southward; common on fueus, 

 piles, etc. 



B. superciliaris Agassiz (Fig. 157). Colony 5 cm. 

 high or less; hypostome inconspicuous; tentacles 15 to 

 20; medusa with yellowish manubrium and black ocelli, 

 10 mm. in diameter: Newport to Greenland; on fucus 

 and shells; Europe. 



2. PERIGONIMUS Sars. Trophosome : colony branch- 

 ing a little and rising from a reticulated hydrorhiza 

 with a gelatinous perisarc and conical hypostome. 

 Gonosome : medusa with 2 or 4 marginal tentacles ; no 

 ocelli: 10 species. 



P. jonesi Osborn and Hargitt. Hydroid colony, 10 

 mm. high or less; hydranth with 16 tentacles; medusa 

 hemispherical with an apical projection, 2 mm. high and broad, with 2 

 long tentacles and 2 additional tentacular bulbs; manubrium short, 

 squarish, with 4 oral lobes: on spider crabs (Libinia) at Cold Spring 

 Harbor, L. I. 



Fig. 156 Bougainvillia 

 carolinensis (Hargitt). 



Fig. 157 



Bougainvillia 



superciliaris 



(Agassiz). 



