NORTH AMKKH'AX KAULY TERTIARY BRYOZOA. 557 



different from the lateral arenlae. The peristomice is irregular, pyriform. the 

 narrowest part below; the peristome is thick and complete; the peristomie is shal- 

 low, but it hides the real form of the aperture which (seen from the interior* i- 

 elongated and elliptical. On the line of the areolae, in the vicinity of the peri- 

 stomice, there is a small, simple, elliptical avicularium somewhat pointed. 



Measurements. Aperture f&a.= 0.10 mm. 7 fZ0=0.55-0.65 mm. 



(interior) \1a =0.0" mm. ' Us=0.25 mm. 



Affinities. The frontal pores and the avicularia are quite variable. 



This species is very close to M<'ni*<-npora (Eschara) semitubulo'sa Retiss. 1869, 

 of the Priabonian of the Vicentin. Unfortunately the latter has not yet been 

 found again and no direct comparison is therefore possible. 



Occurrence. Vicksburgian (Byrain marl) : One-fourth mile west of Wood- 

 ward. Wayne County, Mississippi (common). 



('<>fi;pcs.Cnt, No. 64515, F.S.X.M. 



Genus BRACEBRIDGIA MacGillivray, 1886. 



18SC. Bi-(i<-<-lirk]ffitt MACGILLIVRAY. Descriptions of new or little known polyzoa. part 0, 



Transactions Royal Society of Victoria, p. 8. 

 (Syn. Porosloma CANU. 1907.) 



"Zoarium bilaminate, erect. Apertura subcircular. straighter below, with 

 an internal denticle; peristome thickened, smooth or with a small apicnlate 

 mucro; frequently in the fossils, but rarely in recent specimens, a triangular 

 avicularium immediately below the lower lip; lateral avicularia on the free edges 

 of the zoarium " (MacGillivray). The gonoecia are larger than the usual zooecia. 

 The frontal is partially or totally covered over by a pleurocyst which is more or 

 less confluent with the subjacent olocyst. 



Genotype. Bracebridgia (Porella} cmendata Waters, 1881. 



/t'i'/if/c. Jacksonian Recent. 



The genus Porostomn Canu. 1007, differs from Bracebridr/in only in tin- 

 place of the oral avicularium, which is placed entirely within the peristomie. Its 

 function does not appear different, so it will be necessary to unite the two genera. 



The known species of Bracebridgia are as follows : 



Bracebridgia (Porella) emevilittn Waters, 1881, Miocene and Australian waters. 



lii-iici'briilgia (Porinn) mibxiiJi'itfn Smitt. 187:2. Recent. Florida. 



Bracebridgia (Eschar//) />/_>! i/mut'pha Reuss, 1864. Tongrian. 



Bracebridgia (Kscham) !i/m>biUs Reuss, 1866. Middle Tongrian (=Rupelian). 



Bracebridgia (Porostomn) polymorphum Canu, 1907, not Reu, lsi;'.. (=B. 

 i/i ii/ifiTiiiii. name new) Ypresian. 



liriii-i'liriili/ia incisum Canu. 1907. Ypresian. 



Bracebridgia (Porostomn) ,l,ii',itnin Gregory. Lutetian. 



Bracebridgia (Men!sr t >/><>ni) */'7'renulata Canu, 1907. Ypresian-Lutetian, 

 Bartonian. 



