AET. 14 FOSSIL AND RECENT BRYOZOA CANU AND BASSLEE 119 



,, J A ^ /• 4. • J?ia = 0.15-0.20 mm. 



Measurements. — Apertm'e (mteriorji, /^ r,r. « ^.^ 



^ Ua = 0.20-0.25 mm. 



„ • /. i • Jis = 0.70-0.80 mm. 

 Zooecia (mtenorji, ^ ^^ ^ ^^ 



^ UZ2 = 0.40-0.50 mm. 



Structure. — The operculum is very thin, bell-shaped; two long lat- 

 eral bands placed very near the border serve as attachments for the 

 muscles. The operculum and the mandible of the small peristomial 

 avicularia have the aspect of those of Porella. 



Affinities. — In the list of species of Palmicellaria which we pub- 

 lished in 1923, we forgot a beautiful species from the Enghsh Crag, 

 Palmicellaria (Lepralia) hicornis Busk, 1859. Our American species 

 approaches it very closely but differs from it in its somewhat larger 

 micrometric dimensions, in its larger and more salient ovicell, and in 

 the presence of more than two accessory peristomial avicularia. Our 

 specimens were in reproduction April 12, 1886. 



Occurrence. — Albatross Station D. 2650, Bahama Islands; 23° 34' 

 30'' N.; 76° 34' 00" W.; 369 fms.; coral sand, white ooze. 



Cotypes.—C&t. No. 7565, U.S.N.M. 



Genus UMBONULA Hincks, 1880 



UMBONULA UNDULATA, new species 



Plate 17, Figures 11-13; text Figure 22b 



Description. — The zoarium is free, bilamellar with undulated 

 fronds. The zooecia are distinct, separated by a furrow, elHptical, 

 somewhat elongated ; the frontal is very convex, decorated by four 

 or five pairs of large costules oriented toward a small avicularian 

 umbo which covers the lyrule. The aperture is semielliptical, trans- 

 verse, with rounded lateral angles; it is placed at the bottom of a 

 short peristomie; the peristomice is transverse or elongated. The 

 ovicell is globular, smooth, or costulated. 



Tir ^ A ^ f^a = 0.12mm. 



Measurements. — Aperture-^, 



^ Ua==0.10 mm. 



fX2 = 0.50-0.60 mm. 



Zooeciai, _ __ 



Us = 0.25 mm. 



Variations. — The avicularian umbo is not constant; it is often 



replaced by a sinus of the peristome at the bottom of which the 



lyrule is visible. The operculm is thickened, chitinous, golden yellow; 



it is semielliptical and the proximal border is straight or convex. 



The ovicells are very numerous on the colony and yet the species 



is very rare ; the larvae probably do not know how to choose their 



substratum. 



