50 PROCEEDINGS OF THE XATIOXAL MlSEl'M. 



diaphragms abundantly developed, distinguish Prasopora /lo.ytifa/is 

 from associated bryozoa, while the numerous and strong acanthopores 

 serve to separate it from other speeies of the genus. 



Orciirrencr. — Abundant throughout the Richmond grou]) at most 

 localities in the Ohio Basin, The type of J/, iruichelll was found 

 near Lynchburg, Highland County, Ohio. 



PROBOSCINA FRONDOSA (Nicholson). 



Auloponi Jvondosa i \UK^, Additions to Catal. Foss. Cincinnati (Troup, 1873, p. 15 



(named only). 

 .l/ec/o//vmr/osa Nicholson, (xeol. Surv. Ohio, Pal., II, 1S75, ]>. 2H(i, pi. xxv,tiu:s. ',\-',M>. 

 Froboschia froiido.m Ulrich, Geol. and Nat. Hist. Surv. Minnesota, Final Rep., 



TIT, Pt. 1, 1893, p. 119, pi. I, %. 28. 



The wAvae. Aalopoi'd frondosa is a novien midnni^ since flames never 

 detined the species. Nicholson gives a satisfactory description and 

 good figures of the species and credits the name to James. An excel- 

 lent tigure is given by Ulrich in the work cited above. 



Occurrence. — The typical form is not uncommon in the Corryville 

 member of the McMillan formation at Cincinnati and vicinity. 



PTILODICTYA NODOSA James. 



Plilodictiia nixlosii ,] AMES, Paleontologist, No. 3, iS79, j;. 20. 



Ptilodirtiia nodoxd ri.KK'H, .Jour. Cincinnati Soc. Nat. Hist., IV, 1SS2, pi. vii, 



figs. 2, 2a. 

 I'tUodiciii't varud)>Us Ulkich, (reol. Surv. Illinois, VIII, 1890, p. 304, figs. 2« and t>/(. 

 Ptdodicti/a dintonrnsiK J \yiKs, Paleontologist, No. rt, 1881, p. 38. 

 I'tlIodirti/(i t f ir s .]\yiKs, Paleontologist, No. 5, 1881, ]). 40. 



As suggested l)y ririch's name, J\ nwlahiUfi., this is quite a variable 

 species, the shape of the zoariiun ranging from smooth, narrow, sword- 

 shaped examples scarcely 2 mm. in width to broader nodose fronds 

 reaching a width of lo nnn. or more. James's type specimen of /'. 

 iKxIo.sd^ an old and strongly marked .specimen, was tiguivd by Ulrich 

 in 1882. This author in 18S>0 proposed the new name PfUodictya 

 varhtb'dU for the species on the ground that P. twd<m( was preoccu- 

 pied by Hairs E-scJiai'opora recta var. nodoxn^ a New York Trenton 

 form. At that time Excharopora and PfHodlcfi/d were supposed to 

 r(>prcsent the same genei'ic type, ))ut since Ulrich's t-areful work in 

 Lsi>8 we know these two genera to he distinct. Hall's species and 

 variety being tiie typical forms of Excharopora., Jiilodictya nodosa is 

 not i)reoccupicd and nuiy therefore stand as a valid name. 



'iliis species is distinguislu^d from the associated forms of l*t'do- 

 d'lctyu by its straight, parallel-edged frond. Young specimens have 

 a smooth surfai-e, but after the zoarium attains a width of 8 mm. or 

 more the macuhe dtn'elops as strong nodes arranged in more or less 



