NO. 2 osburn: eastern pacific bryozoa — cheilostomata 343 



Family HlppOpoHnidae new family 



In this group the frontal consists of a thick olocyst or pleurocyst, 

 usually imperforate except for the marginal areolar pores; the ovicell 

 is hyperstomial ; the aperture in the typical genus Hippoporina is con- 

 siderably elongated proximal to the cardelles but this is not true of all 

 the genera ; the operculum also varies in the proportions of the proximal 

 part, it is well chitinized and provided with a sclerite or thickening at 

 the margin or at some distance within the border and to this sclerite 

 the muscles of the operculum are attached. The cardelles are usually 

 strong and the operculum constricted on the sides. Avicularia are usually 

 present and in some species there are oral spines. In some of the genera 

 there are additional pores, which at least leave the central area free 

 proximal to the aperture. 



Key to the Genera of Hippoporinidae 



1. Ovicell perforated with numerous pores 2 



Ovicell imperforate 6 



2. Ovicell closed by the operculum 3 



Ovicell not closed by the operculum 4 



3. Frontal smooth and porcellanous Hippomenella 



Frontal granular or reticular Hippomonavella 



4. Poster deep and rounded Gemelliporella 



Poster more or less transverse 5 



5. Poster with a v-shaped sinus ; suboral avicularium . . . Lacerna 

 Poster straight, without sinus ; suboral avicularium . Hippothyris 



6. Avicularium small, median, suboral ; poster transverse . Aimulosia 

 No median suboral avicularium 7 



7. Poster broadly transverse and without a sinus 8 



Poster deep, rounded, or with a median sinus 9 



8. Zooecia erect and cumulate Hippoporidra 



Zooecia procumbent ; avicularium suboral, 



asymmetrical Hippoporella 



9. Poster with a rounded or v-shaped sinus .... Stephanosella 

 Poster deep and rounded, no sinus ; few areolar pores ... 10 



10. Zoarium broadly encrusting; frontal porcellanous . Hippoporina 

 Zoarium uniserial or erect and branching . . . Gemelliporina 



