OPHRYOCEUriNA. 



[ 557 ] 



ORBULINA. 



the encystiiiji- process; when they leave the 

 jelly, a'posterior ring of cilia is formed, as 

 iu Vortkella, aud the aiiimids swiui with 

 the tail tirst. 



This organism bears some resemblance to 

 CoccocMoris among the Palmellacese, yet it 

 appears decidedly animal. 

 O. EivhorHii, on Anacharis. 

 BiBL. Ehr. In/us. 292 ; Stein, In f. ; Cla- 

 parede et hachmanu, Etudes  Kent, Inf. 735. 

 OPHRYOCEKCINA, Ehr.— A 'family 

 of In fii soria . See Th ac heli x a. 



OPHRYODEN'DRON, Clap, et Each.— 

 A genus of Acinetina. 



C/iar. Acinetina with the suckers at- 

 tached to a long retractile proboscis. 

 Six species ; marine. 

 (). ahitiimim, on Ciunpnnularia. 

 BiBL. Clap, et Each. Etudes^ 381 ; Kent, 

 Inf. 849. 



"OPHRYOGEE NA, Ehr.—A genus of 

 Holotrichous Infusoria, of the family Bursa- 

 rina. 



Char. Ovate ; a fronial eye-spot ; cilia in 

 longitudinal rows; a watch-glass-shaped 

 vibratile membrane near the muuth. Fresh- 

 water. 



Five species. Stein remarks that, on 

 treating these animals with acetic acid, the 

 cilia became converted into a dense network 

 of curved and geniculate hairs, some as long 

 as the bodv. 



0.atra\V\. 31. fig. 51). Body ovate, 

 compressed, black, acute posteriorly ; eye- 

 spot black, marginal ; cilia whitish ; length 

 1-180". 



O. acuminata, brown ; eye-spot red. 

 O.Jlavicatis, yellowi.-h ; eve-spot red. 

 BiBL. Ehr. Inf. 360; Stein, Inf. 240; 

 Diij. Inf. 506; Lieberkiihn, Ann. N. H. 

 1866, x\-iii. 319 ; Claparede et Lachmanu, 

 Etudes, 256 ; Kent, Inf. 532. 



OPHRYOSCO'EEX, St.— A genus of 

 Peritrichous Infusoria. Free, ovate-elon- 

 gate, with a Vorticella-Yike peristome ; 

 middle of the back surrounded by a row of 

 stout setEe ; a long posterior style-like pro- 

 cess. 2 species ; in the rumen aud reticulum 

 of ruminants. (Kent, Inf. 652.) 



OPISTHIOT'KICHA, Perty.— A genus 

 of Infusoria. 



Char. Small, .cylindrical or pyriform. 

 Cilia on body fine, those on posterior part 

 large. 0. tenuis, in bog-pools. 

 BiBT.. Pertv, Lebensf. 150. 

 OPIS'THO'DOX, St*ein.—A genus of Hy- 

 potrichous Infusoria. Free, ovate, dorsally 

 convex, vcj lically plane, t jlialc ; mouth 



near the posterior half, w-ith a cylindrical 

 rod-fascicle. O. niemeccerms ; freshwater. 

 (Kent, Inf. 749. ) 



OPISTIIOTRICiriA, Kt.— A genus of 

 llypotrichous Infusoria. Free, ovate ; 

 frontal, ventral, aud anal styles as in Ojci/- 

 triclui, also with caudal setas. 2 species j 

 freshwater. (Kent, Inf. 785.) 



ORBICUEI'NA, Eamk.— A genus of 

 porcellaneous Foraminifera. Discoidal, equi- 

 lateral, greatly compressed, very variable 

 according to age; forming an embracing, 

 very regular spire when young, subse- 

 quently growing into a more or less perfect 

 disk, almost uudistinguishable from Orhito- 

 lites. Chambers very narrow, curved, and 

 divided throughout their length into nu- 

 merous minute cavities (chamberlets) by 

 perpendicidar partitions, transverse to the 

 spiral coil. Orifices very numerous, round, 

 in rows along the septal plane on the outer 

 margin of the shell. 



Living in tropical seas (O. odunca, PI. 23. 

 fig. 19) ; fossil in the Tertiaries. 



BiBL. Carpenter, Phil. 1): 1856, 547; 

 For. 93. 



ORBITOrpES, D'Orb.— One of the hya- 

 line Foraminifera, related to NummuUtes 

 and often mistaken for it. Eenticular ; 

 thick or thin ; smooth, granular, or radiate ; 

 composed of a median plane of chamberlets 

 arranged cyclically, and of very numerous 

 layers of compressed chamberlets above and 

 below. 



Fossil only ; in the Upper Chalk, and 

 Eower and Middle Tertiaries. 



BiBL. Gumbel, Abh. baijer. Ale. 1868, x. 

 070. 



ORBITOEI'NA. See Patellixa aud 



POKOSPH^RA. 



ORBITOLI'TES, Lamarck (Orbulites).— 

 Aporcellaneous Foraminifer, nearOrbicidina, 

 but distinguished by the chambers being 

 arranged in concentric circles. 



Inhabiting tropical seas. 



O. complanaius (PI. 23. fig. 17) — Sorites 

 and Amjjhisonts, Ehr. ; fossil in the Lias, 

 Chalk, and Tertiaries. 



BiBL. Morris, Brit. Foss. 39 ; Carpenter, 

 Phil. Tr. 1856, 181 ; For. 105. 



ORBULI'NA, D'Orb.- A hyahne Fora- 

 minifer, consisting either of a single spheri- 

 cal chamber, or of a large globular chamber 

 enclosing a small Globigerine group of 

 earliercells. Perforations numerous, minute 

 and of two sizes; but single orifice doubtful. 

 O. uni versa CPl. 24. fig. 1). Recent, and 

 fossil as far back as the Lias, 



