OPHRYOCERCINA. 



[ 557 ] 



ORBULINA. 



the encysting process ; when they leave the 

 jelly, a posterior ring of cilia is formed, as 

 in Vorticella, and the animals swim with 

 the tail first. 



This organism bears some resemblance to 

 Coccochloris among the Palmellaceae, yet it 

 appears decidedly animal. 

 O. Eichornii, on Anacharis. 

 BIBL. Ehr. Infus. 292 ; Stein, Inf. ; Cla- 

 parede et Lachmann, Etudes ; Kent, Inf. 735. 

 OPHRYOCERCI'NA, Ehr.- A family 

 of Infusoria. See TRACHELINA. 



OPHRYODEN'DRON, Clap, et Lach. 

 A genus of Acinetina. 



Char. Acinetina with the suckers at- 

 tached to a long retractile proboscis. 

 Six species ; marine. 

 O. abietinum, on Campanularia. 

 BIBL. Clap, et Lach. Etudes, 381 j Kent, 

 Inf. 849. 



OPHRYOGLENA, Ehr. A genus of 

 Holotrichous Infusoria, of the family Bursa- 

 rina. 



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

 longitudinal rows; a watch-glass-shaped 

 vibratile membrane near the mouth. 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 body. 



O. atra (PI 31. tig. 51). Body ovate, 

 compressed, black, acute posteriorly ; eye- 

 spot black, marginal ; cilia whitish ; length 

 1-180". 



O. acuminata, brown ; eye-spot red. 

 O. ftavicans, yellowish ; eye-spot red. 

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

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

 1856, xviii. 319 ; Claparede et Lachmann, 

 Etudes, 256 ; Kent, Inf. 532. 



OPHRYOSCO'LEX, St. A genus of 

 Peritrichous Infusoria. Free, ovate-elon- 

 gate, with a Vorticella-\ike peristome; 

 middle of the back surrounded by a row of 

 stout setae ; a long posterior style-like pro- 

 cess. 2 species j in the rumen and reticulum 

 of ruminants. (Kent, Inf. 652.) 



OPISTHIOT'RICHA, Perty. A genus 

 of Infusoria. 



Char. Small, cylindrical or pyriform 



Cilia on body fine, those on posterior part 



large. O. tennis, in bog-pools. 



BIBL. Perty, Lebensf. 150. 



OPISTHODON, Stein. A genus of Hy- 



potrichous Infusoria. Free, ovate, dorsally 



convex, vertically plane, ciliate ; mouth 



near the posterior half, with a cylindrical 

 rod-fascicle. O. niemeccensis : freshwater. 

 (Kent, Inf. 749.) 



OPISf HOTRICH'IA, Kt. A genus of 

 Hypotrichous Infusoria. Free, ovate ; 

 frontal, ventral, and anal styles as in Oxy- 

 tricha, also with caudal setae. 2 species ; 

 freshwater. (Kent, Inf. 785.) 



ORBICULI'NA, Lamk. 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 undistiuguishable from Orbito- 

 lites. Chambers very narrow, curved, and 

 divided throughout their length into nu- 

 merous minute cavities (chamberlets) by 

 perpendicular 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. adunca, PI. 23. 

 fig. 19) ; fossil in the Tertiaries. 



BIBL. Carpenter, Phil. Tr. 1856, 547: 

 For. 93. 



ORBITOI'DES, D'Orb. One of the hya- 

 line Foraminifera, related to Nummulites 

 and often mistaken for it. Lenticular; 

 thick or thin ; smooth, granular, or radiate j 

 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 

 Lower and Middle Tertiaries. 



BIBX. Giinibel, Abh. bayer. Ak. 1868, x. 

 670. 



ORBITOLI'NA. See PATELLINA and 



POROSPHJERA. 



ORBITOLI'TES, Lamarck (Orbulites). 

 A porcellaneous Foraminifer, near Orbiculina, 

 but distinguished by the chambers being 

 arranged in concentric circles. 



Inhabiting tropical seas. 



O. complanatus (PI. 23. fig. 17 ) = Sorites 

 and Amphisorus, Ehr. j fossil in the Lias, 

 Chalk, and Tertiaries. 



BIBL. Morris, Brit. Foss. 39 : Carpenter, 

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



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

 minifer, consisting either of a single spheri- 

 cal chamber, or of a large globular chamber 

 enclosing a small Globigerine group of 

 earlier cells. Perforations numerous, minute 

 and of two sizes ; but single orifice doubtful. 

 O. universa(P\. 24. fig. 1). Recent, and 

 fossil as far back as the Lias. 



