582 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



It differs from Perigastrella depressa, of which it has the zooecial form and 

 general appearance, in the presence of its spines, in its frontal granulations, and in 

 its labial mucro. 



The difference between it and ILinicuclopora parajuncta is quite small; it 

 differs from it, however, in its visible areolae. its much larger labial mucro, and 

 in its frontal granulations. 



It differs from Perigastrella ovoidca in its smaller dimensions. (Ls=0.50 and 

 not 0.75 mm.) and in its transversal and trapezoidal apertura. 



Occurrence. Middle Jacksonian: Wilmington, North Carolina (common); 

 near Lenuds Ferry, South Carolina (common). 



C'otypes.Cnt. No. fi4200. U.S.N.M. 



PERIGASTRELLA DEPRESSA, new species. 



Plate 73. figs. 10-13. 



Description. The zoarium incrusts bryozoa and shells. The zooecia are 

 very little elongated, distinct, irregularly hexagonal ; the frontal is little convex, 

 bordered by very small areolae, and formed of a nearly smooth pleurocyst detach- 

 able from the subjacent olocyst. The apertura is semilunar, transverse, with a 

 straight or slightly convex proximal border; the peristome is scarcely salient; its 

 proximal border is depressed, never salient, sometimes inclined toward the aper- 

 tura. The ovicell is large, smooth, partially fixed to the distal zooecium: its orifice 

 is little visible exteriorly. 



,, {^,7=0.06-0.08 mm. . {7^=0.50 mm. 



Measurement*. Apertura i, , nl /ooecium , 



Ua=0.l2-0.l4 mm. Ife=0.40-0.o0 mm. 



Variations. The zooecial form of this species is rather variable and can not 

 serve for determination. The areolae are invisible most of the time ; only the 

 perfect specimens are provided with them. But the essential characters of this 

 species are easy to recognize : orifice of the ovicell invisible, entire absence of salient 

 labial mucro. 



Affinities. This species much resembles Perigastrella trapezoidea; it differs 

 from it in its still flatter frontal, in the absence of a salient labial mucro, and in its 

 almost smooth zooecia. 



It differs from Hemicyclopora parajuncta in its areolae, sometimes Visible, in 

 the absence of labial mucro, and in its ovicell, which is better attached, more fixed 

 to the distal zooecium. 



Occurrence. Middle Jacksonian: Wilmington, North Carolina (common) ; near 

 Lenuds Ferry, South Carolina (rare). 



Gotypes.C&t. No. 64201, U.S.N.M. 



PERIGASTRELLA RECTILINEATA. new species. 



Plate 73, figs. 14-19. 



Description. The zoarium incrusts shells and bryozoa; the zooecia are disposed 

 in linear rows. The zooecia are distinct, elongated, elliptical ; the frontal is smooth, 



