304 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Occurrence.— D. 4807. Cape Tsiuka, Sea of Japan; 41° 36' 12" N.; 

 140° 36' E. 

 Holotype— Cat. No. 8057, U.S.N.M. 



SCHIZOMAVELLA CORNUTA, new species 



Plate 34, figs. 3, 4 



Description. — The zoarium is free and unilamellar, creeping usu- 

 ally over sponges. The zooecia are distinct, separated by a deep 

 furrow, elongated, elliptical or subrectangular, arranged in linear 

 series; the frontal is convex, garnished with numerous, small tremo- 

 pores and with a small, median, triangular avicularium with beak 

 raised in the form of a horn. The apertura is large, suborbicular, 

 somewhat transverse; the peristome is thin, little salient, complete. 

 The ovicell is large, globular, of the same structure as the frontal, 



Fig. 128. — Schizomavella Canu and Bassler, 1917 

 A, B. S. cornuta, new species. Opercula, X85, showing variations. C. S. 

 ambita granulosa, new variety. Operculum X85. D, E. S. simplex, new species. 

 Operculum X85 and another example highly magnified. 



decorated with a very small median carina and a large circular area, 

 and closed by the operculum. 

 Measurements. — 



Apertura!^ = - 12 mm ' Zooeciajf* -°'^™ mm ' 



\la =0.15 mm. \lz =0.30-0.35 mm. 



Affinities. — The small median avicularium is lacking sometimes; it 

 is then replaced by a large spathulate avicularium arranged later- 

 ally. The operculum is fragile. 



This species differs from Schizomavella auriculata Hassall, 1842, in 

 its broader and shallow rimule and in its triangular instead of pori- 

 form avicularium. It differs from Schizomavella linearis Hassall, 

 1841, in the presence of a median avicularium, in its suborbicular 

 operculum of quite different form and in the absence of small lateral 

 avicularia. 



The arrangement of the zooecia in linear series is general in this 

 genus; it appears to form a secondary, generic characteristic more 

 constant than the arrangement of the avicularia. 



Biology. — Our specimens were living. They were in reproduction 

 and fixation in November, 1904, and February, 1908. This species is 



