ACA. — AMP.] 



MOLLUSCOIDA. 



291 



Family Theonoid.*:. — Scenellopora. 



Family Trematoporidje. — Acanthoclema, Amplexopora, Atactopora, Atacto- 



porella, Bactropora, Chilotrypa, Diamesopora, Homotrypa, Homotry- 



pella, Neraataxis, Nicholsonella, Orthopora, Trematella, Treraatopora, 



Tropidopora, 

 Family Tubuliporid^e. — Berenicea, Clonopora, Cystopora, Hederella, Her- 



nodia, Stomatopora. 



Acanthocladia, King, 1849, Ann. and Mag. 

 Nat. Hist., 2d ser., vol. 3, p. 389. [Ety. 

 akantha, spine ; klados, branch.] Stem 

 symmetrically and bilaterally branched, 

 more or less on one plane ; rarely bi- 

 furcating; branches short, simple, oc- 

 casionally elongated and becoming 

 bilaterally branched; celluliferous on 

 one side only ; cell apertures circular 

 and arranged in three or more longi- 

 tudinal series, separated by dividing 

 ridges. Type A. anceps. 



americana, Swallow, 1858, Trans. St. Louis 

 Acad. Sci., vol. 1, p. 180, Permian Gr. 



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

 111., vol. 8, pi. 65, Up. Coal Meas. 

 Acanthoclema, Hall, 1887, Pal. N. Y., vol. 

 6, p. 72. [Ety. akantha, spine ; klema, 

 twig.] Ramose, solid, cells arising from 

 a central axis ; cell apertures oval, in 

 longitudinal parallel rows, about ten on 

 a branch, separated by longitudinal 

 ridges ; between the apertures, in the 

 longitudinal direction, there are spini- 

 form nodes. Type A. alternatum. 



alternatum, Hall, 1881, (Trematopora al- 

 ternata,) Bryozoans of the Up. Held. 

 Gr., and Pal. N. Y., vol. 6, p. 72, Up. 

 Held. Gr. 



bispinulatum, Hall, 1881, (Callopora bi- 

 spinulata, (Trans. Alb. Inst., vol. 10, p. 

 882, and Pal. N. Y., vol. 6, p. 182, 

 Ham. Gr. 



confluens, Ulrich, 1888, (Rhombopora con- 

 fluens,) Bull. Denisou Univ., p. 91, 

 Cuyahoga Shales. 



divergens, Hall, 1887. Pal. N. Y., vol. 6, p. 

 73, Up. Held Gr. 



ovatum, Hall, 1887, Pal. N. Y., vol. 6, p. 

 73, Up. Held. Gr. 



scutulatum, Hall, 1881, (Trematopora 

 scutulata,) Trans. Alb. Inst., vol. 10, p. 

 180, and Pal. N. Y., vol. 6, p. 190, 

 Ham. Gr. 



sulcatum, Hall, 1887, Pal. N. Y., vol. 6, p. 

 192, Ham. Gr. 



triseriale, Hall, 1883, (Stictopora trise- 

 rialis.) Rep. St. Geol. and Pal. N. Y., 

 vol. 6, p. 74, Up. Held. Gr. 

 Acrogenia, Hall, 1884, Rep. St. Geol. p. 51. 

 [Ety. akros, sharp; genea, growth.] 

 Frond ramose ; two branches proceed- 

 ing from the truncate termination of 

 each preceding one; base of each 

 division obconical, terete above and 



strongly striated, gradually becoming 

 flattened and celluliferous; margins 

 noncelluliferous ; apertures in rows 

 separated by 

 ridges, cen- 

 tral range of 

 a pertures 

 the smaller. 

 Type A. pro- 

 lifera. 

 prolifera, Hall, 

 1884, Rep. 

 St. Geol., p. 

 52, and Pal. 

 N. Y., vol. 

 6, p. 267, 

 Ham. Gr. 



ACTINOTKYPA, 



Ulrich, Geo. 

 Sur I 1 vol FlG ' 448— Acr °g enia prolifera. 

 8, p. 386, (in press.) [Ety. aktin, a ray ; 

 trupa, an opening.] Like Dichotrypa. 

 Cell apertures showing the projecting 

 ends of from eight to ten vertical septa- 

 like ridges, that extend down on the 

 inner side of the tubular vestibule 

 nearly or quite to the primitive aper- 

 tures. Type A. peculiaris. 



peculiaris, Rominger, 1866, (Fistulipora 

 peculiaris,) Proc. Acad. Nat. Sci. Phil., 

 p. 10, Keokuk Gr. 

 Alecto, Lamouroux, 1821, Exposi. Method. 

 It was preoccupied by Leach in the 

 class Echinodermata, when Lamouroux 

 used it, and hence Stomatopora is used 

 in its place. 



auloporoides, see Stomatopora auloporo- 

 ides. 



canadensis, see Hederella canadensis. 



confusa, see Stomatopora confusa. 



frondosa, see Stomatopora frondosa. 



inflata, see Stomatopora inflata. 



nexilis, see Stomatopora nexilis. 

 Amplexopora, Ulrich, 1882, Jour. Cin. Soc. 

 Nat. Hist., vol. 5, p. 154. [Ety. amplexu.% 

 an encircling ; poros, pore.] Ramose ; 

 cells of one kind only ; walls thin in 

 the axial part of the branches, but 

 thicker in the peripheral region ; acan- 

 thopores numerous. Type A. cingu- 

 lata. 



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

 vol. 8, pi. 36, Hud. Riv. Gr. 



canadensis, Foord, 1883, Cont. to Micro- 

 palaeontology, p. 17, Trenton Gr. 



