86 BULLETIN 16 5, UNITED STATES NATIONAL MUSEUM 



Affinities. — Acanthionella typica is the type of the genus as chosen 

 by Canu and Bassler in 1917, so that it is with it that other species 

 should be compared. The genus is not exclusively American, for to 

 the known species must be added Lepralia {Mucronella) russelli 

 Pergens, 1893, from the Maastrichtian of Limbourg. 



Eschara striata Goldfuss, 1826, from the Maastrichtian of Lim- 

 bourg was classed by Voigt, 1930, in Kleldionella, but this species 

 bears an ascopore, which structure is lacking in that genus. 



Ulrich and Bassler, 1907, considered the encrusting specimens as 

 belonging to Mucronella aspera Ulrich, 1907, from the Eocene at 

 Upper Marlboro, Md., but now that encrusting specimens with bi- 

 lamellar expansions have been discovered they no longer maintain 

 this opinion. 



We made the first study in 1920 of the genus Acanthionella. The 

 section of this species published by us in 1920, made from a very 

 calcified specimen, shows clearly that the ovicell is not closed by 

 the operculum, so that the genus is quite distinct from Psilosecos. 

 However, it is unquestionable that the two genera are closely related, 

 and in the future they may be placed in a new family close to the 

 Reteporidae and Smittinidae. 



Occurrence. — Vincentown limesand : Timber Creek and Mullica 

 Hill, N.J. (Gabb and Horn) ; common at Vincentown and near 

 Blackwooclstown, N.J.; rare at Noxontown Millpond and 2 miles 

 southeast of Odessa, Del. 



Plesiotypes.— U.S.N. M. Nos. 73895, 73896. 



Genus KLEIDIONELLA Canu and Bassler, 1917 



KLEIDIONELLA(?) TRABECULIFERA, new species 



Plate 15, Figure 8 



Description. — The zoarium is bilamellar. The zooecia are indis- 

 tinct, unoriented, urceolate in appearance ; they are surmounted by 

 a very thick peristomie erect or oblique; the frontal is convex, 

 smooth, more or less visible. The peristomies are bound together 

 by trabeculae, leaving between them large irregular and polygonal 

 spaces. The apertura is semielliptical, transverse; the proximal 

 border bears a salient triangular mucron, the peristome bears two 

 small avicularia arranged laterally and symmetrically. The large 

 interzooecial avicularia are oval, with denticles, spatulate or not. 



Measurements. — 



, \ha = 0.1 mm. Diameter of peristomie, 0.2-0.25 mm. 



Apertura^ , _ i . A OA . . . 



I/«=0.14 mm. 18-20 zooecia in 4 sq. mm. 



Variations. — It is difficult to estimate the number of zooecia on 



a given surface because of the great irregularity of the polygonal 



