NO. 2 OSBURN: eastern pacific BRYOZOA CHEILOSTOMATA 363 



Genus HIPPOTHYRIS, new genus 



The frontal is a pleurocyst with several rows of pores and a com- 

 paratively small imperforate central area; aperture with the anter semi- 

 circular and the poster wide and shallow, the proximal border nearly 

 straight, cardelles moderate in size; peristome thin and somewhat 

 elevated, without spines, enclosing on the proximal border a small median 

 avicularium. Ovicell globular, recumbent and not embedded, per- 

 forated, not closed by the operculum. Genotype, Hippothyris emplastra 

 new species. 



Hippothyris emplastra new species 

 Plate 40, figs. 13-14 



The zoarium forms a thin encrustation on siliceous sponges. The 

 zooecia are large, 0.80 to 1.20 mm long by 0.65 to 0.90 mm wide, 

 ovate, hexagonal or quadrate in form, very distinct. The frontal is a 

 granulated pleurocyst with several rows of pores and a comparatively 

 small imperforate central area which is delicately reticulate resembling 

 a small breast-plate ; the imperforate area is about as wide as the per- 

 forated area on each side. The aperture is subquadrangular, the sides 

 parallel, the poster about as wide as the anter and very shallow with the 

 proximal border nearly straight ; condyles moderate ; broader than long, 

 0.18 to 0.20 mm wide by 0.14 to 0.16 mm long. The peristome is thin, 

 a little elevated and on the proximal border encloses a small median 

 avicularium with its short-triangular mandible directed vertically. The 

 avicularian chamber is very small and umbonate in form. Spines want- 

 ing. IVIultiporous septulae present. 



The ovicell is hyperstomial, globular and prominent, recumbent on 

 the distal zooecium but not embedded, perforated and the rather large 

 pores slightly collared ; width about 0.35 mm but appearing small in 

 comparison with the large zooecia. 



Type, U. S. Nat. Mus.. 11029; paratype AHF no. 75. 



Type locality. Albatross Station D.5682, Magdalena Bay, on the 

 west coast of Lower California, at 491 fms. Two colonies encrusting a 

 siliceous sponge. 



Genus HIPPOMENELLA Canu and Bassler, 1917 



"Hippoporininae with a finely perforate hyperstomial ovicell. Ori- 

 fice with a shallow but wide poster separated from the anter by promi- 

 nent condyles. Frontal avicularia generally paired forming prominent 



