MEE. MER.] 



BRACHIOPODA. 



353 



MEEKELLA, White & St. John, 1868, Trans. 

 Chi. Acad. Sci., vol. 1, p. 120. [Ety. 

 proper name.] Globose, rather longer 

 than wide, plications large, hinge-line 

 shorter than greatest breadth of the 

 valves ; dorsal valve most prominent 

 on the umbo, beak incurved, no me- 

 sial sinus ; cardinal process long, curv- 

 ing backward in front of the pseudo- 

 deltidium, and haying upon each side a 

 wing- like expansion, which is curved 

 up at its outer edge forming an elon- 

 gated dental fossette; ventral valve 

 more convex, cardinal area high, no 

 median septum ; two broad dental la- 

 mella?, continuous from the cardinal 

 teeth to the beak, pass directly in front 

 of the sutures between the cardinal 

 area and the pseudodeltidium, and 

 thence, slightly diverging, extend for- 

 ward along the bottom of the valve 

 about half-way to the front, the an- 

 terior margins of the lancellse arching 

 backward and upward to the dental 

 processes ; a cross section shows three 

 chambers opening anteriorly into the 

 shell. Type M. striato-costata. 

 striato-costata, Cox, 1857, (Plicatula stri- 

 ato-costata,) Geo. Rep. Ky., vol. 3, p. 

 568, Coal Meas. 



FIG. 580. Meekella striatocostata. Dorsal and 

 ventral view. 



Megarderis sequiradiata, see Rensselseria 

 sequiradiata. 



cumberlandix, see Rensselseria cumber- 

 landiae. 



elliptica, see Rensselseria elliptica. 



elongata, see Amphigenia elongata. 



laevis, see Rensselseria Isevis. 



rmUabilis, see Rensselseria mutabilis. 



ovalis, see Rensselseria ovalis. 



ovoides, see Rensselseria ovoides. 



subtrigonalis, see Amphigenia elongata var. 

 subtrigonalis. 



suessana, see Rensselseria suessana. 

 MERISTA, Suess, 1851, Jahrb. Geol. Reichs. 

 Austalt, vol. 2, p. 150. [Ety. meros, a 

 part.] General form like Athyris, usu- 

 ally mesial fold and sinus poorly de- 

 fined ; the principal stems forming the 

 spirals attach to the hinge plate, in- 

 cline forward toward the interior of 

 the shell, then abruptly bend back- 

 ward and make a curve facing the bot- 

 tom of the dorsal valve, and, after con- 

 verging to about half their length, again 

 diverge toward the front and form the 



first spiral coil ; there are 10 or 12 whorls 

 in each spiral; the genus is distin- 

 guished by a shoe-lifter process under 

 the beak of the ventral valve, consisting 

 of two roof-shaped plates, fixed by their 

 lateral margins to the medio-longitudi- 

 nal region of the valve, and with their 

 narrow end fitting under the extremity 

 of the beak. Type M. herculea. 

 arcuata, see Meristella arcuata. 



FIG. 581. Merista bella. Dorsal and anterior 



view. 



bella, Hall, 1857, 10th Rep. N. Y. St. Mus. 

 Nat. Hist., p. 92, and Pal. N. Y., vol. 3, 

 p. 248, Low. Held. Gr. 



bisulcata, Vanuxem, 1843, (Atrypa bisul- 

 cata,) Geo. Rep. 3d Dist. N. Y., p. 112, 

 and Pal. N. Y., vol. 3, p. 253, Low. 

 Held. Gr. 



elongata, Hall, 1859, (Camarium elonga- 

 tum,) Pal. N. Y., vol. 3, p. 488, Low. 

 Held. Gr. 



houghtoni, Winchell, 1862, Proc. Acad. 

 Nat. Sci., vol. 6, 2d ser., p. 407, Port- 

 age Gr. 



Isevis, see Meristella Isevis. 



lata, Hall, 1859, Pal. N. Y., vol. 3, p. 431, 

 Oriskany sandstone. 



lens, Wincbell, 1866, Rep. Low. Penin. 

 Mich., p. 94, Ham. Gr. 



meeki, Hall, 1857, 10th Rep. N. Y. St. 

 Mus. Nat, Hist., p. 97, and Pal. N. Y., 

 vol. 3, p. 252, Low. Held. Gr. 



princeps, see Meristella princeps. 



subquadrata. Hall, 1857, 10th Rep. N. Y 

 St. Mus. Nat. Hist., p. 93, and Pal 

 N. Y., vol. 3, p. 249, Low. Held. Gr. 



sulcata, Vanuxem, 1842, (Atrypa sulcata,) 

 Geo. Rep. N. Y., p. 112, Water- 

 lime Gr. 



typus, Hall, 1859, (Camarium typus.) 

 Pal. N. Y., vol. 3, p. 487, Low. 

 Held. Gr. 



MERISTELLA, Hall, 1860, 13th Rep. N. Y 

 St. Mus. Nat. Hist., p. 74. [Ety. di- 

 minutive of Merista.'] Shells variable 

 in form, ovoid or transverse ; valves 

 unequally convex, with or without a 

 median fold and sinus; beak of ventral 

 valve imperforate, incurved over the 

 beak of the other valve; no area; 

 valves articulating by teeth and sock- 

 ets; surface smooth or with fine con- 

 centric strise; interior of dorsal valve 

 having a longitudinal septum and 

 the upper part of the ventral valve 

 a deep subtriangular muscular im- 

 pression, which unites with the rostral 

 cavity ; spires are continued from their 

 origin obliquely backward into the 

 cavity of the ventral valve, and then, 



