EAKLY TERTIARY CHEILOSTOME BRYOZOA. 35 



cell is large and deeply embedded in the distal zooecia. The ovi- 

 celled zooecia haAe a large apertiira. 



Genotype. — Metracol'posa rohusta., new species. Jacksonian. 



METRACOLPOSA ROBUSTA, new species. 



Plate 3, fig. 6. 



Description. — The zoarium is free, bilamellar, large (1 to 2 centi- 

 meters in width), solid, robust. The zoa?cia are distinct, elongated, 

 elliptical; the frontal is somewhat convex; the costules are trans- 

 verse at the top, radial below ; they number from seven to nine pairs 

 and are separated by four or five large lacunae ; the lumen pores are 

 small and irregular. The apertura is transverse, semielliptical with 

 a straight or slightly convex proximal border; it is bordered dis- 

 tally by a very thin, incomplete peristome. The ovicell is large and 

 deeply embedded in the distal zocecia, elongated, salient, convex, 

 decorated in front with a deltoid carina ; it opens above the apertura 

 and probably was closed by the operculum when it opened. The 

 apertura of the ovicelled zooecia is larger. A small triangular distal 

 avicularium is placed either on the right or left of the apertura. 



Measv/rements. — Apertura (ordinarv) L 'r^ 



^ ^ ^ \la =0.20 mm. 



. ^ / • 11 TV fAa=0.12— O.Mmm. 

 Apertura (ovicelled) , ^„q „ on 

 ^ ^ ^ (Z(Z=0.28— 0.30 mm. 



. [Zs=0.96— 1.00 mm. 



^^^"^"Iz^ =0.44-0.46 mm. 



The zooecial width is rather variable; there are some zooecia which 

 measure 0.51 mm., in which case the costules are radially arranged. 



The avicularia are rather rare; their point is directed toward the 

 median axis of the zocecia above the apertura; sometimes they are 

 vertical ; when well preserved, they have a calcareous pivot. 



Occun'ence. — Middle Jacksonian (Castle Hayne beds) : Wilming- 

 ton, North Carolina (very common). 



Type.—C^i. No. 62586, U.S.N.M. 



ACANTHOCELLA, new genus. 



{AcantTui^ spine.) 



The costules bear a row of very prominent lumen pores and are 

 separated by lacunae of greater or less size. The apertura is semi- 

 lunar. The ovicell is hyperstomial and its orifice is not in contact 

 with the operculum. 



Genotype. — Crihrilina tuhulifera Hincks, 1881, from Australian 

 seas. 



Range. — Jacksonian-Eecent. 



