592 



SYSTEMATIC HISTORY OF THE IXFI'SOEIA. 



than the other ; hence the appearance of 

 a main stem and a subsidiary branch. 

 The zooids terminating the ramifica- 

 tions are pear-shaped, the ^\^dth nearly 

 equalling the length, and almost glo- 

 bular when the periston! is contracted. 

 They are of a greyish hue. The rounded, 

 lip-like, ciliated periston! is of less dia- 

 meter than the widest part of the body ; 



and its entire space is occupied by the 

 rotary organ, which is only a little ele- 

 vated above it when extended. The 

 nucleus is elongated and veri!!icular. 

 The average lei!gth of the bodv is 1-360" 

 to 1-280"'- and the width "1-456" to 

 1-336". Geiiimation may be frequently 

 seen, the buds growing fi'om the fore 

 part of the body behind the peristom. 



Genus OPEECULARIA (XXIX. 4; XXX. 1, 2, 27).~Branched pedicle, 

 stiff and rigid, supporting dissimilar corpuscles (zooids). The anamalcules 

 have two lips ; the superior one, supported by a muscle, is somewhat like a 

 lid (operculum), which is a characteristic. Operculana = Epistylis with dis- 

 similar corpuscles. The organs of locomotion consist of a wreath of cilia, 

 and a long muscle within the body ; this raises or depresses the frontal region, 

 in the form of an upper lip. Food is taken into, and its effete portions dis- 

 charged from the large vestibulum situated in front and rather to one side, 

 and to and from which the alimentary canal is seen running. Self-division 

 and the separation of the zooids from the stalk may be frequently observed. 

 The large dissimilar bodies occur singly beneath the animalcules, more espe- 

 cially in the axillae of the branches ; some are very large and egg-shaped, 

 with hairs at their point, and only a small, round, non-vibratile opening. 

 Ehrenberg observes that such are most probably parasitic bodies. In all 

 probability, however, they are encysted corpuscles. 



The following characters, contrasted with those of Epistiflis, are given by 

 Stein. The peristom is, in Opercidcn^ia, merely a single border, neither 

 ciliated, thickened, nor everted in a campanulate manner. The body, there- 

 fore, is elongated, ovoid, constantly narrowed anteriorly, and simply ti^uncated. 

 The opening of the peristom, which also forms that of the mouth, extends as 

 a mde and deep cavity (the vestibulum) to the oesophagus, which is prolonged 

 far into the body as a narrow digestive tube. A distinction between this last 

 canal and the oesophagus is indicated by a group of three or four strong cilia 

 placed at its commencement. The rotary organ springs from the wide oral 

 cavity, on one side, by a narrow point, which is the apex of its trumpet- 

 shaped figure. The base of this long conical sac is formed by its ciliated disc, 

 which is thrust much above the peristom when extended, but can be drawn 

 down upon it and close it : the whole organ is very moveable. The older 

 observers looked upon the rotary organ as a valve or lid ; and Ehrenberg 

 supposed it to have a long retractile muscle which could close it upon the 

 mouth. However, no muscle exists within the pedicle of the organ ; for this is 

 a hollow sac fiUed with the same substance as the general cavity of the body, 

 and in direct communication with it. The pedicle of the ciliary disc is longer 

 and more moveable than that of VorticeUa and Epistylis. The genus Opercu- 

 laria is fui'ther distinguished by the presence of a delicate membranous, trans- 

 parent process which stands out from the throat like an internal^ fixed colfar, 

 and is elevated above the peristom, forming a sort of under lip to the rotary 

 organ. Whether this is ciliated, or onlj^ a vibrating membrane, Stein remains in 

 doubt. It is the same structure as is referred to by Ehrenberg in his note on 

 Epistylis ? ( Opercularid) nutans as a protrusile bladder-like process (see p. 590). 



Opercularia articulata (V. Ojoercu- 

 laria, M.) (xxx. 1) occm's as a little 

 shrub, 1-6" to 1-4" high, white and 

 dichotomous ; carmine and indigo readily 

 states he saw as 



taken ; and Ehrenbei 



many as forty-four stomach-cells filled, 

 resembling a girdle in the middle of the 

 body. The stalk is very delicately 

 striated in a longitudinal direction, and 

 shows, at its ramifications, a transverse 



