NORTH A.MEIMCAN EARLY TERTIARY BRYOZOA. 445 



METRADOLIUM GRANDE, new species. 



Plate 55, figs. 12-14. 



Description. The zoarium is free, bilamellar. erect; the fronds are dicho- 

 toiuous, foliaceous or subcylindrical ; (In- two lamellae are inseparable. The zooecia 

 are very lar<i<\ elongated, indistinct laterally; the frontal is convex, thick, formed 

 of a tremocyst with large pores. The peristomice is large, elongated; the rimule- 

 spiramen is large, rounded. The oral avicularium is large, transverse adjacent to 

 the peristomice or placed in the peristomie. 



Measurements.- Peristomice /i;>r>= 0.35-0.45 mm. . fZs=0.90-1.00 mm. 



. 



(exterior) lZpe=0.25-0.40 mm. ia IZ2=0.50 mm. 



Affinities. When the avicularium is exterior the rimule-spiramen is quite well 

 formed (fig. 13) ; when it is hidden in the peristomie the rimule becomes very 

 irregular and deeper. It is the lengthening of the tubules of the tremocyst which 

 increase and deform the peristomice and augment the external dimensions of the 

 zooecia. 



This species differs from HI etradoliitm transversum in its large rimule. its 

 elongated and nontransverse peristomice (hpe=Q.%5 and not 0.15 mm.) and its 

 large tremopores. 



It differs from Mc.tradoli.um sulciferum in the absence of frontal sulci and its 

 smaller general micrometric dimensions. 



Occurrence. Middle Jacksonian : Near Lenucls Ferry, South Carolina (very 

 rare) ; Rich Hill, Crawford County, Georgia (rare) ; Eutaw Springs, South Caro- 

 lina (rare) ; one-half mile southeast of Georgia Kaolin Company Mine. Twiggs 

 County. Georgia (rare). 



Jacksonian (Zeuglodon zone) : Bluff on south side of Suck Creek. Clarke 

 County, Mississippi (very rare). 



Cotypes.G&t. Nos. 64116, 64117, U.S.N.M. 



METRADOLIUM CONVENIENS, new species. 

 Plate 56, figs. 16-21. 



Description. The zoarium is free, bilamellar, erect; the fronds are foliaceous, 

 fiat, or undulated, branching; the two lamellae, back to back, are inseparable. The 

 zooecia are elongated, little distinct laterally ; the frontal is convex, thick ; it is 

 formed of a tremocyst with small tubules arranged in quincunx, placed on a very 

 thin olocyst with small corresponding pores. The apertura is subround; the peri- 

 stomice is very elongated, elliptical ; the rimule-spiramen is more or less visible and 

 always symmetrical. The ovicell is globular, little salient, ornamented with tremo- 

 pores similar to those of the frontal; its peristome is transverse in the form of a 

 lunar-crescent; it is hyperstomial, very large, and opens largely into the peristomie. 

 Near the peristomice there are two elliptical avicularia, replaced often by a single 

 larger and more salient one. 



