ART. ATA.] 



MOLL USCOIDA. 



ARTHROCLEMA, Billings, 1862, Pal. Foss., vol. 

 1, p. 54. [Ety. arthron, joint; klrma, 

 twig.] Cylindrical jointed stem, with 

 long, slender-jointed branches ; pores 

 oval. Type A. pulchellum. 



angulare, Ulrich, (in press), Geo. Sur. 

 111., vol. 8, pi. 29, Hud. Riv. Gr. 



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

 vol. 8, Trenton Gr. 



pulchellum, Billings, 1862, Pal. Foss., 

 vol. 1, p. 54, Trenton Gr. (See p. 329.) 



spiniforme, see Helopora spiniformia. 

 Arthronema, Ulrich, 1882, Jour. Gin. Soc. 

 Nat. Hist., vol. 5, p. 160. The name 

 was preoccupied. See Arthrostylus. 



FIG. 454. Arthropora 

 shafferi. Magnified 

 section. 



FIG. 453. Arthropora shafferi. 



curium, see Arthrostylus curtus. 

 tenue, see Arthrostylus tenuis. 



AKTHROPORA, Ulrich, 

 1882, Jour. Cin. 

 Soc. Nat. Hist., 

 vol. 5, p. 152. 

 [Ety. arthron, a 

 joint ; poros, per- 

 foration.] Zoar- 

 ium like Sticto- 

 pora, but in 

 short, jointed, 

 branching seg- 

 ments ; cell aper- 

 tures subcircu- 

 lar, and sur- 

 rounded by interstitial pits. Type A. 

 shafferi. 



shafferi, Meek, 1872, 

 (Stictopora shaf- 

 feri,) Proc. Acad. 

 Nat. Sci., p. 317, 

 and Ohio Pal., vol. 

 1, p. 69, Hud. Riv. 

 Gr. 



simplex, Ulrich, 1886, 

 14th Rep. Geo. Sur. 

 Minn., p. 65, Tren- 

 ton Gr. 

 ARTHROSTYLUS, Ulrich, 



1888 Am p ori i FIG. 455. Arthropora 

 1888, Am Geol., 8nafferi . Tangential 

 vol. 1, p. 230. [Ety. section x 50. 

 arthron, joint; 



stylos, pillar.] Ramose, composed of 

 subcylindrical segments, swollen at 

 each end, celluliferous on one side, 

 striated on the other; cells between ele- 

 vated lines. Type A. tenuis. 

 curtus, Ulrich, 1882, (Arthronema cur- 

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

 p. 161, Hud. Riv. Gr. 



tenuis, Ulrich, 1882, (Arthronema tenue,) 

 Jour. Cin. Soc. Nat. Hist., vol. 5, p. 

 160, Trenton Gr. 



ASCODICTYON, Nicholson, 1877, Ann. and 

 Mag. Nat. Hist., 4th ser., vol. 19, p. 

 463. [ Ety. askos, leather bottle ; dictyon, 

 net.] Organism composite, parasitic, 

 composed of numerous calcareous 

 cells; minutely perforated. Type A. 

 lusiforme. It is probably a sponge. 



fusiforme, Nicholson, 1877, Ann. and 

 Mag. Nat. Hist., 4th ser., vol. 19, p. 463, 

 Ham. Gr. 



stellatum, Nicholson, 1877, Ann. and Mag. 

 Nat. Hist., 4th ser., vol. 19, p. 464, 

 Ham. Gr. 



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

 Hist., vol. 5, p. 155. [Ety. aspis, shield ; 

 poros, perforation.] Thin, free expan- 

 sions; concentrically wrinkled and 

 striated epitheca on the lower side; 

 cells gradually increasing in size toward 

 the center of the convex expansion ; 

 interstitial cells numerous ; diaphragms 

 cross both kinds of tubes; spiniform 

 tubuli present. Type A. areolata. 



areolata, Ulrich, 1883, Jour. Cin. Soc. Nat. 

 Hist., vol. 6, p. 164, Utica Slate. 



caliculus, James, 1875, (Chetetes calicu- 

 lus,) Int. Catal. Cin. Foss., p. 1, and 

 Nicholson Struct, and Affin. Montic., 

 p. 165, Utica Slate. 



parasitica, Ulrich, 1886, 14th Rep. Geo. 



Sur. Minn., p. 90, Trenton Gr. 

 ATACTOPORA, Ulrich, 1879, Jour. Cin. Soc. 

 Nat. Hist., vol. 2, p. 119. [Ety. atactos, 

 without regularity ; poros, pore.] In- 

 crusting; surface with monticules or 

 maculae ; cell apertures petaloid, sur- 

 rounded by rows of blunt spines; in- 

 terstitial cells in clusters; tube walls 

 inflected; diaphragms present. Type 

 A. hirsuta. 



hirsuta, Ulrich, 1879, Jour. Cin. Soc. Nat. 

 Hist,, vol. 2, p. 120, Hud. Riv. Gr. 



maculata, Ulrich, 1879, Jour. Cin. Soc. 

 Nat. Hist., vol. 2, p. 121, Hud. 

 Riv. Gr. 



multigranosa, see Atactoporella multi- 

 granosa. 



mundula, see Atactoporella mundula. 



septosa, see Amplexopora septosa. 



?subramosa, Ulrich, 1879, Jour. Cin. 

 Soc. Nat. Hist., vol. 2, p. 124, Hud. 

 Riv. Gr. 



tenella, see Atactoporella tenella. 

 ATACTOPORELLA, Ulrich, 1883, Jour. Cin. 

 Soc. Nat. Hist., vol. 6, p. 247. [Ety. 

 diminutive of Atactopora.] Incrust- 

 ing; surface with monticules or ma- 

 culae ; cell apertures petaloid ; inter- 

 stitial cells numerous ; spiniform tubuli 

 and diaphragms. Type A. typicalis. 



multigranosa, Ulrich, 1879, (Atactopora 

 multigranosa,) Jour. Cin. Soc. Nat. 

 Hist., vol. 2, p. 122, Hud. Riv. Gr. 



mundula, Ulrich, 1879, Atactopora mun- 

 dula,) Jour Cin. Soc. Nat. Hist, vol. 2, 

 p. 123, Hud. Riv. Gf. 



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