AKT. 14 FOSSIL. AND EECENT BRYOZOA CANU AND BASSLER 85 



the spiranien and the peristomice, in the presence of frontal granu- 

 lations and a single avicularium, in its greater micrometric dimensions, 

 and in its crescentic spiramen. It is much larger than Stenopsis 

 unirostris Canu and Bassler which we have discovered in the Philip- 

 pines. Our specimens creep over serpulae and nullipores. They 

 were in reproduction in March, 1885. 



Occurrence. — Albatross Station D. 2405, Gulf of Mexico; 28° 45' 

 00" N.; 85° 02' 00" W.; 30 fms.; gray sand, broken coral. 



Plesioty pes. —Cat. No. 7599, U.S.N.M. 



Family SCLERODOMIDAE Levinsen, 1909 



Genus SEMIHASWELLIA Canu and Bassler, 1917 



SEMIHASWELLIA SINUOSA, new species 



Plate 15, Figures 1-4 



Description. — The zoarium is articulated, the segments are long 

 (10 mm.), subcylindrical, sinuous, with the zooecia on one face only; 

 the anterior face bears tremopores arranged at the bottom of longi- 

 tudinal, irregular, shallow sulci, and small, round, widely spaced 

 avicularia. The zooecia are little distinct, much elongated; the 

 frontal is convex and formed of a tremocyst with tubules the orifices 

 of which are arranged at the bottom of longitudinal shallow sulci. 

 The ascopore is small, round, placed on the median axis and at the 

 base of the peristomie; the latter is somewhat salient and termi- 

 nated by a fringed and orbicular peristome. The ovicell is globular, 

 arranged laterally and opening into the peristomie. The base of 

 articulation (basis ramae) is formed by a frontolateral eminence 

 pierced by a large central pore surrounded by smaller pores; the 

 flexible fibers are issued not only from the central pore but also from 

 the small neighboring tremopores. 



'Lz = 0.50 mm.; diameter of peristome. 



Measurements. — Zooecias, \ ^^ ' t ^ j- 



lz = 0.25 mm.; diameter of segments, 



. 0.50 mm. 



Structure. — In longitudinal section the zooecial walls are very 

 thick; the tubules are very wide, although their orifice is very small, 

 the ascopore is wide somewhat oblique, opening in the interior into 

 the peristomie at the level of the operculum. 



The ovicell is very remarkable and unique; instead of being 

 arranged distally as in the genotype, it is placed laterally between 

 the peristome and the ascopore. We have not, unfortunately, 

 enough specimens to make a section of the ovicell and verify if it is 

 a dissymetric peristomial ovicell or an ordinary hyperstomial ovicell. 



Affinities.— The genotype SemiJiaswellia prohoscidea Waters, 1889, 

 has been dredged at a great depth around St. Thomas (West Indies). 

 The presence of other species of the same genus in the Gulf of Mexico 



