NO. 2 OSBURN: eastern pacific BRYOZOA CHEILOSTOMATA 509 



Costazia procumbens new species 

 Plate 63, figs. 8-10 



The zoarium encrusts small stems and rises into narrow, erect, cylin- 

 drical branches 1 to 2 mm in diameter, tapering at the tips, branching 

 rarely and irregularly, rough in appearance. The zooecia are more or 

 less procumbent, entirely so at the growing tips, those of the secondary 

 layers half erected or more; the size moderately large, the procumbent 

 ones 0.65 to 0.85 mm long by 0.40 to 0.50 mm wide. The frontal, which 

 is more exposed than usual in the genus, is moderately ventricose, smooth 

 in young individuals, with a row of marginal pores and an irregular 

 second row of scattered pores (the central area always imperforate) ; 

 with increasing calcification the pores are carried upward, some of them 

 to the base of the peristome, and the frontal surface becomes radiately 

 ribbed to a slight degree. The peristome is high and nearly erect, com- 

 plete in the infertile zooecia and fusing with the sides of the ovicell 

 in the fertile ones ; on the sides are the usual lateral oral avicularia, 

 raised slightly above the level of the rim, the small rounded mandibles 

 tilted toward each other; the oral avicularia are located slightly more 

 proximally than usual and the secondary aperture is roughly pyriform, 

 the proximal part between the avicularia narrowed to form a secondary 

 sinus. The primary aperture is round with the addition of a semi-circular 

 sinus, length 0,18 and width 0.15 mm. Frontal avicularia are infrequent, 

 regularly oval, length 0.30 and width 0.20 mm, the rostrum thin-walled 

 and only slightly raised. 



The ovicell is very prominent, rounded, large (0.35 to 0.40 mm 

 broad), the frontal area with a marginal row of pores separated by 

 radiating ribs. The details of the ovicell, as well as those of the front 

 are difficult to determine until the glossy covering membrane is removed. 



The sinus of the primary aperture is broader and more semicircular 

 and the zooecia more procumbent than usual in the genus ; but the nature 

 of the front, of the paired oral avicularia, the characters of the ovicell 

 and the interzooecial avicularia are definitely those of Costazia. 



Type,AHFno. 112. 



Type locality, Hancock Station 1659-48, S. of Avalon Bay, Santa 

 Catalina Island, southern California, 46 fathoms, 33 °19'53"N, 

 118°17'51"W. Also at stations 1449-42, Newport Harbor, on a float, 

 and 1012-39, of? Pyramid Cove, San Clemente Island, southern Cali- 

 fornia, 55 fms; and 1251-41, south of San Benito Islands, 66 fms, and 

 1078, S. of San Benito Islands, 92 fms, 28°12'05''N, 117°52'55''W, 

 Lower California. 



