318 



MOLLUSCOIDA. 



[PRO. PTI. 



PROUTELLA, Ulrich, (in press,) Geo. Sur. 111., 

 vol. 8, p. 403. [Ety. proper name.] 

 Discoid, thin, free, lower surface con- 

 vex and lined with a concentrically 

 wrinkled epitheca; primary zooecia sub- 

 tubular, the succeeding ones shorter, 

 all rather thin-walled ; aperture broad- 

 elliptical, surrounded by a narrow, 

 sloping area, hexagonal in outline ; 

 when perfect, with a depressed delicate 

 calcareous plate, that closes a little 

 less than two-thirds of the opening, 

 the orifice left being subtriangular in 

 form, without thickened margins, and 

 situated at the anterior side ; with age, 

 a second, third, and more layers of zo- 

 oscia are developed directly over the | 

 first, so that they gradually form a zoojcial 

 tube seemingly having the cavity inter- ! 

 sected by incomplete diaphragms ; \ 

 these appear to spring from the 

 posterior wall, and extend about 

 one-half the distance across. 

 Type Cycloporadiscoidea. Syn.? 

 for Cyclopora. 



discoidea, Prout, 1860, (Cyclopora 

 discoidea,) Trans. St. Louis Acad. 

 Sci., vol. 1, p. 578, Keokuk Gr. 



Pteropora duogeneris, Hall, syn. for 



Taeniopora exigua. 

 Ptilionella, Hall, 1884, Rep. St. 



Geol., p. 56, syn. for Reptaria. 

 nodata, see Reptaria nodata. 

 penniformis, see Reptaria penni- 

 formis. 



PTILODICTYA, Lonsdale, 1839, Murch. 

 Sil. Syst., p. 676. [Ety. ptilon, 

 feather; dictyon, net] The cor- 

 rect orthography is Ptilodictyon. 

 Zoarium pointed below, articu- 

 lating into a spreading base, above 

 a leaf -like expansion, which is some- 

 times lobed at the distal extremity, 

 celluliferous on both faces, divided by 

 a mesial lamina ; margin without cells ; 

 apertures circular or subquadrate ; no 

 intercellular tissue. Type P. lanceolata. 



arguta, see Stictopora arguta. 

 bipunctata, Van Cleve, 1883, 12th Rep. 



Ind. Geol. and Nat. Hist., p. 266, Ni- 



ara Gr. 

 briareus, Ulrich, 1882, Jour. Cin. Soc. Nat. 



Hist., vol. 5, .p. 164, Trenton Gr. 

 canadensis, Billings, 1866, Catal. Sil. Foss. 



Antic., p. 9, Hud. Riv. Gr. 

 carbonaria, see Stictopora carbonaria. 

 cosciniformis, see Coscinella cosdniformis. 

 dictyota, Meek, 1873, Hayden's 6th Rep. 



Geo. Sur. Terr., p. 465, Subcarboniferous. 

 emacerata, see Dicranopora emacerata. 

 excettens, see Phsenopora excellens. 

 explicans, Safford, 1869, Geo. of Tenn. Not 



defined, 

 falciformis, Nicholson, 1875, Ohio Pal., vol. 



2, p. 259, Hud. Riv. Gr. 

 fenestelliformis, Nicholson, 1875, Ohio 



Pal., vol. 2, p. 263, Hud. Riv. Gr. 



FIG. 502. -Ptllodictya maculate. Vertical section 

 x 35, showing spinous process. 



acuminata, James, 1876, Int. Catal. Cin. 

 Foss., p. 3, Hud. Riv. Gr. Not well de- 

 fined. 



alcyone, see Pachydictya alcypne. 



arctipora, see Bythopora arctipora. 



FIG. 503. Ptilodictya raagniflca. Sections x 50. 



flagellum, Nicholson, 1875, Ohio Pal., vol. 



2, p. 26?, Hud. Riv. Gr. 

 fragilis, see Dicranopora fragilis. 

 gladiola, Billings, 1866, Catal. Sil. Foss., 



Antic., p. 10, Anticosti Gr. 

 hilli, James, 1882, (as figured by Ulrich,) 



Jour. Cin. Soc. Nat. Hist., vol. 5. pi. 7, 



Trenton Gr. 



internodia, see Dicranopora internodia. 

 libana, Safford, 1869, Geo. of Tenn. p. 286, 



Trenton (Jr. 

 lirata, Hall, 1874, (Escharopora lirata,) 



26th Rep. N. Y. St. Mus. Nat. Hist., p. 



100, Low. Held. Gr. 

 maculata, Ulrich, 1882, Jour Cin. Soc. 



Nat. Hist., vol. 5, p. 163, Hud. Riv. Gr. 

 niHgnifica, S. A. Miller, 1878, Jour Cin. Soc. 



Nat. Hist, vol. 1, p. 100, Hud. Riv. Gr. 

 meeki, Nicholson, 1874, Geo. Mag. n. s., 



vol. 1, p. 123, Corniferous and Ham. Gr. 

 multiramis, Safford. Not defined, 

 nebulosa, Hall, 1874, (Escharopora nebu- 



losa,) 26th Rep. N. Y. St. Mus. Nat. 



Hist., p. 99, Low. Held. Gr. 



nitidula, see Dicranopora nitidula. 



nodosa, James, 1882, (as figured by Ul- 

 rich), Jour. Cin. Soc. Nat. Hist., vol. 5, 

 pi. 7, Hud. Riv. Gr. The name was 

 preoccupied. See P. variabilis. 



