332 



BRA CHIOPODA. 



[ACA. AMB. 



FAMILY RHYNCHONELLID^. Camarella, Camarophoria, Eatonia, Eichwaldia, 



Leiorhynchus, Rhynchonella, Rhynchotreta, Stenoschisma. 

 FAMILY SIPHONOTRETID.E. Acrothele, Acrotreta, Iphidse, Kutorgina, Schiz- 



ambon, Siphonotreta. 

 FAMILY SPIRIFERID^E. Arabocoelia, Cyrtia, Cyrtina, Martinia, Spirifera, Spirif- 



erina, Syntrielasma, Syringothyris, Trigonotreta. 

 FAMILY STROPHOMENID.E. Leptsena, Streptorhynchus, Strophodonta, Stro- 



phomena, Strophonella. 

 FAMILY TEREBRATULID^E. Centronella, Cryptonella, Leptocoelia, Rensselseria, 



Terebratula, Tropidoleptus, Vitulina, Waldheimia. 



FAMILY TRIMERELLID^E. Dinobolus, Lingulops, Monomerella, Trimerella. 

 FAMILY TRIPLESITDJE. Triplesia. 



ACAMBONA, White, 1862, Proc. Bost. Soc. Nat. 

 Hist., vol. 9, p. 27. [Ety ake, point; 

 ambon, umbo.] Syn. for Eumetria. 

 prima, see Eumetria prim a. 

 ACROTHELE, Linnarsson, 1876, Bihangtill K. 

 Vet. Akad. Handl., p. 20, Swed. Acad. 

 Sci. on the Brachiopoda of the Para- 

 doxides beds. [Ety. akros, pointed ; 

 thelf, nipple ; from the apex of the 

 valve.] Shell thin, corneous, subcircu- 

 lar in outline, depressed, concentrically ' 

 marked, and sometimes radiated ; apex ! 

 of ventral valve teat-like ; subcentral or i 

 near the posterior margin, perforated ; ' 

 dorsal valve slightly convex, posterior ' 

 margin slightly reflexed, and internally j 

 a low median longitudinal septum rep- '< 

 resented by an impression in the cast. 



Type A. coriacea. 

 dichotoma, Walcott, i 

 1885, Monogr. U. S. 

 Geo. Sur., vol. 8, p. 

 14, Up. Taconic. 

 matthewi, Hartt, 1868, 

 (Lingula matthewi,) 

 Acad. Geol., p. 644, 

 St. John Gr. 

 subsidua, White, 1874, 

 (Acrotreta subdsidua, ) 

 Rep. Invert. Foss., p. 6, and Geo. Sur. W. 

 100th Mer., vol. 4, p. 34, Up. Taconic. 

 Acr o t r e t a , a 

 Kutorga, 

 1848, Uber 

 die Siphon- 

 otretse aus 

 den Ver- 

 1 1 :n i dl un- 

 gen der 

 Kaiserlich - 

 en Miner- 



alogisc hen FIG. 533. Acrotreta gemma. 

 Small outline figures natural 

 8lze a and dorsal valveg . 



6, ventral valve; d, area or 



B20, an ventral valve.which shows a 

 nviHa/vn'o central groove ; /, area of an- 

 avidson S otner specimen having no 

 B r a c h i o - groove ; e, side view. 

 poda, vol. 



1, p. 133. [Ety. akros, the top or sum- 

 mit ; tretos, perforated.] Shell triangu- 



FIG. 532. Acroth- 

 ele subsidua. In- 

 terior of dorsal 

 valve enlarged. 



lur Jahr., 

 260, and 



lar, larger valve conical, false area flat, 

 bent back at right angles to the margin 

 of the valve, longitudinally grooved 

 along the center, and perforated at its 

 extremity by a small circular aperture, 

 the lines of growth encircle the shell 

 and pass uninterruptedly over the false 

 area; the smaller valve flat, operculi- 

 fprm, smooth, marked by concentric 

 lines of growth ; valves unarticulated. 

 Type A. subconica. 



attenuata. 1873, 6th Rep. Hayden's Geo. 

 Sur. Terr., p. 463, Up. Taconic. 



baileyi, Matthew, 1885, Trans. Roy. Soc. 

 Can., p. 36, St. John Gr. 



gemma, Billings, 1865, Pal. Foss., vol. 1. 

 p. 216, Quebec Gr. 



gulielma, Matthew, 1885, Trans. Roy. Soc. 

 Can., p. 37, St. John Gr. 



pyxidicula, White, 1874, Rep. Invert. 

 Foss., p. 9, and Geo. Sur. W. 100th 

 Mer., vol. 4, p. 53, Potsdam Gr. 



subsidua, see Acrothele subsidua. 

 MgUops, Hall, 1850, 3d Rep. N. Y. St. Mus. 

 Nat. Hist., p. 179. The name was pre- 

 occupied for a genus in botany ; beside 

 it was founded on the cast of a Lamel- 

 libranch. 



subcarinata. Name not to be retained. 

 AMBOCCELIA, Hall, 1860, 13th Rep. N. Y. St. 

 Mus. Nat. Hist., p. 71. [Ety. amban, 

 umbo ; koilos, the belly.] Distinguished 

 from Orthis, Spirifera, etc., by the in- 

 terior markings in the ventral valve, 

 the thickened margins of the fissure are 

 produced in short, strong teeth, but 

 there is scarcely any extension of the 

 dental plates; in the dorsal valve the 

 bases of the crura continue attached to 

 the inner surface of the valve for more 

 than one-third of its length before becom- 

 ing free ; there is a lateral projection from 

 these crural bases bounding the teeth 

 sockets ; the cardinal process is elon- 

 gate, lying between the crura, and is 

 bifurcated at the outer extremity as in 

 Cyrtina; the muscular impressions are 

 below the middle of the valve, often 

 near the front and quadruple ; the dor- 

 sal valve being concave, flat or de- 



