4-2 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 93 



PORELLA OPERCULATA, n. sp. 



Plate 8, fig. 6 



Description. — ^The zoarium is free, cylindrical, long. The zooecia 

 are indistinct with thick walls, very long ; the frontal is convex and 

 covered with numerous tubular tremopores. The peristome is thick, 

 smooth, very little salient ; the peristomice is elliptical, elongated ; 

 the peristomie is deep and formed by the thickening of the zooecial 

 walls ; it contains in the proximal portion a large oblique avicularium, 

 triangular, with pivot ; the beak is oriented distally ; the proximal por- 

 tion is free or closed by a suborbicular, calcareous operculum. The 

 ovicell is large, salient, globular, ornamented with a double row of 

 large pores separated by short radial costules. 



Measurements. — 



: 0.27-0.30 mm 

 : 0.17-0.20 mm 



Occurrence. — Janjukian beds at 

 Victoria. 



Coty pes.— U.S.N. M. no. 85842. 



. (lip- 

 Penstomice-< , 



Zooecium 

 Anticline 



L::= 1.10-1.20 mm 



/- = o.50 (?) mm 



Creek, Dartmoor, 



PORELLA EXCAVATA, n. sp. 



Plate 7, fig. II 



Description. — The zoarium is free, bilamellar ; the fronds are cylin- 

 drical, flabellate or lamellar and narrow, bifurcated ; there are from 

 one to seven longitudinal rows of zooecia on each branch. The zooecia 

 are distinct, separated by a salient thread, elongated, rectangular ; 

 the frontal is flat and perforated with tremopores. The peristome is 

 thin, salient, smooth ; it is indented in the proximal portion by a 

 linear sinus at the bottom of which there is a flat lyrule ; the sinus 

 is prolonged on the median axis of the zooecium by a small, linear 

 excavation in which is placed a small, triangular, thin, elongated 

 avicularium ; the peristomice is orbicular and small. The ovicell is 

 very small, globular, smooth. 



Measurements. — 



„ . . (hp = 0.i2 mm . rL.cr = 0.75-0.90 mm 



Feristomice-< ,^ _ , Zooecuim^ , 



1 Ip = 0.12 mm 1 /.J = 0.25-0.30 mm 



Occurrence. — Janjukian beds at Anticline Creek, Dartmoor, 



Victoria. 



Cotypes.—U.S.N.M. no. 85838. 



