58 BULLETIN 165, UNITED STATES NATIONAL MUSEUM 



salient, convex. The peristomice of the ovicelled zooecia is sub- 

 orbicular. 

 Measurements. — 



Zooecia ]z> = 65mm . [hp = 0A mm. 



(including L; =04mm _ * Peristomicej Zp=015mm 



avicularia) j 



16 zooecia in 4 sq. mm. 



Affinities.— The structure here is close to that of the Galeopsidae. 

 A.n arch arising from the oral avicularia covers the aperture, leav- 

 ing an empty space, a sort of pseudospiramen. This characteristic 

 is peculiar to the American species of Tricephalopora, and we have 

 found it even in the Tertiary. 11 The European species have on the 

 contrary two symmetrical pseudospiramens with the protective arch 

 bifurcated. Tricephalopora acutirostris differs from T. prolifera 

 Gabb and Horn, 1862, in the distal orientation of its avicularia. 



Occurrence.— Vincentown limesand : Very rare at Vincentown and 

 near Blackwoodstown, N.J. 



Hole-type.— U.S.N.M. No. 73922. 



TRICEPHALOPORA INCRASSATA, new species 



Plate 13, Figure 5 



Description. — The zoarium encrusts debris. The zooecia are dis- 

 tinct, separated by a deep furrow, elongated, swollen, capitate; the 

 frontal is convex, very thick, smooth, bearing at the center a small 

 costulated circular area and terminated by a long peristomie en- 

 larged distally. There is no pseudospiramen. The costules to the 

 number of four are extremely small and often indiscernible. The 

 apertura is buried at the bottom of the peristomie. The peristom- 

 ice is suborbicular, irregular. The ovicell is hyperstomial, not 

 closed by the operculum, buried in the distal zooecium, opening into 

 the peristomie, small, convex, smooth, little salient exteriorly. The 

 oral avicularia are triangular, with a pivot, transverse, pointed. 



Measurements. — 



I Lz = 0.5-0.6 mm. „ . . . \hp= 0.09-0.1 mm. 

 Zooecmm^ = ()35 _ 04 mm Pen S tomice|^ = ao& _ 012 mm 



20-22 zooecia in 4 sq. mm. 



Structure.— -In this species the epicalcification is very intense ; not 

 only does it cover almost all the frontal, hiding the costules, but it 

 also much thickens the primitive protective arch, which is then sup- 

 ported on the apertural bar, suppressing thus the pseudospiramen. 



Affinities.— This new species differs from T. prolifera Gabb and 

 Horn, 1862, in its smaller dimensions and in the absence of a pseudo- 



« See Oephyrotes convexus and O. quadriserinlis Canu and Bassler, TJ.S.Nat.Mus.Bull. 

 106, pp. 301, 304, 1920. 



