332 



BRACHIOPODA. 



[ACA. — AMB. 



Family Rhynchonellidje. — Caraarella, Cahiarophoria, Eatonia, Eichwaldia, 



Leiorhynchus, Rhynchonella, Rhynchotreta, Stenoschisma. 

 Family Siphonotretid^e. — Acrothele, Acrotreta, Iphidse, KutorgiDa, Schiz- 



ambon, Siphonotreta. 

 Family Spiriferid^e. — Ambocoelia, Cyrtia, Cyrtina, Martinia, Spirifera, Spirif- 



erina, Syntrielasrna, Syringothyris, Trigonotreta. 

 Family Strophomenid^e. — Leptsena, Streptorhynchus, Strophodonta, Stro- 



phomena, StrophoneJla. 

 Family Terebratulidje. — Centronella, Cryptonella, Leptocudia, Rensselteria, 



Terebratula, Tropidoleptus, Vitulina, Waldheimia. 

 Family Trimerellid^e. — Dinobolus, Liugulops, Monomerella, Trimerella. 

 Family Triplesiid.e. — Triplegia. 



Acambona, White, 1862, Proc. BoBt. Soc. Nat. 

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

 ambon, umbo.] Syn. for Eumetria. 

 prima, see Eumetria prima. 

 Acrothei.k, Linnarsson, 1876, Bihangtill K. 

 Vet. Akad. Handl., p. 20, Swed. A. ad. 

 Sci. on the Brachiopoda of the Para- 

 doxides beds. [Ety. akros, pointed ; 

 thele, 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 

 near the posterior margin, perforated; 

 dorsal valve slightly convex, posterior 

 margin slightly reflexed, and internally 

 a low median longitudinal septum rep 

 resented by an impression in the cast. 



Type A. coriaci a. 

 diehotoma, Walcott, 



1885, Monogr. U. S. 



Geo. Sur., vol. 8, p. 



14, Up. Taconic. 

 matthewi, Ilartt, 1868, 



(Lingula matth< 



Acad. Geo!., p. 644, 



St. John (Jr. 

 suhsidna, White, 1874, 



(Acrotreta subdsidua, ) 

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

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

 Acr o t r e t a , 

 Kutorga , 

 1848, Uber 

 die Siphon- 

 otretee aus 

 den Ver- 

 han d 1 u n - 

 gen der 

 Kaiserlich - 

 en Miner- 

 alogisch e n Fig. 533. — Acrotreta gemma- 

 Gesellscaf t 8 . ma11 outline figures natural 

 fur Jahr., 

 p. 260, and 

 Davidson's 

 Brachio- 

 poda, vol. 

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

 mit ; tretos, perforated.] Shell triangu- 



Fio. 532.— Acroth- 

 ele sabsidua. In- 

 terior Of (lOIMll 



valve enlarged. 



size ; a and c, dorsal valves ; 

 b, ventral valve; d, area of 

 ventral valve.which shows a 

 cential groove ; /, area of an- 

 other specimen having no 

 groove ; e, side view. 



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- 

 form, smooth, marked by concentric 

 lines of growth ; valves unarticulated. 

 Type A. subconica. 



attenuata, 1873, 6th Rep. Ilayden's (ieo. 

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



bailevi, Matthew, 1885, Trans. Roy. 

 (an, p. :;ii, St. JohnGr. 



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

 p. 216, Quebec < i i . 



gulielma, Matthew, 188"), Trans. Roy. 

 Can., p. 37, St. John Or, 



pyxidicula, White, 1874, Rep. Divert. 

 Foss., p. 9, and (ieo. Sur. W. 100th 

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



subsidua, see Acrothele subsidna. 

 uEgilops, 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- 

 lihranch. 



subcarinata. Name not to be retained. 

 Amboco2Lia, Hall, 1860, 13th Rep. N. Y. St. 

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

 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 itslength before becom- 

 ing free ; there is a lateral projection from 

 these crural bases bounding the teeth 



v 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- 



