734 



ORDER PERITRICHA. 



what resemble in shape the mouthpiece of a clarionet. Length of lorica 



1-400". 



Hab. — Fresh water, attached to the leg joints of Gammarns piilex. 



This species, while closely resembling the preceding in size and general con- 

 tour, is readily distinguished from it by the peculiar character of the hp-like ante- 

 rior 'prolongation, or free edge of the peristome-border. As remarked by Stem, 

 the longitudinally plicate structure of this organ exhibits a remarkable conformity 

 with the longitudinally plicate membrane or pharyngeal rod-fascicle of Prorodon, 

 Chi/odon, and other Holotrichous and Hypotrichous types, and with which mdeed it 

 is apparently homologically identical. Examples of this species associated with 

 Spirochona gemfnipam have been recently received by the author through J^Ir. Thomas 

 Bolton. 



Sub-Family III. OPHRYDINA. 



Animalcules excreting and inhabiting a soft mucilaginous solitary 

 sheath or compound zoocytium. 



Genus XX. OPHIONELLA, S. K. 



(Dim. Greek, op/iis, snake.) 



Animalcules solitary, elongate, highly contractile, secreting a mucila- 

 ginous investing sheath, to the bottom of which they are not permanently 

 attached ; oral system as in Vorticella and Ophrydhim ; endoplast linear ; 

 contractile vesicle spherical, anteriorly situated. 



The representatives of this genus resemble isolated stalkless zooids of the genus 

 Ophrydhim, from which, however, they differ in not being permanently attached to 

 the bottom of their mucilaginous domicile in either a sessile manner or through the 

 medium of a pedicle. The single species so far observed is an inhabitant of fresh 

 water. 



Ophionella picta, S. K. Pl. XLI. Figs. 22 and 23. 



Body transparent, elongate vermiform, subcylindrical, slightly inflated 

 posteriorly, highly elastic, protruding when expanded to a considerable 

 distance beyond the aperture of its sheath, the cuticular surface smooth or 

 finely granular. Length of extended body, I-150". 



Hab. — Fresh water, on aquatic plants. 



This species was obtained by the author in some abundance in the spring 

 of the year 1874, its characteristic mucilaginous dwellings being constructed within 

 the angles formed by the filamentous branchlets of a leaf of Myriophyllum spicatum. 

 A single example of the same form was likewise encountered, but at the time 

 imperfectly observed, on Anacharis received from Mr. Thos. Bolton, of Birming- 

 ham, in December of the year 1872. The attitude assumed by the animalcules in 

 their expanded condition is very elegant, they at such times protruding nearly one-half 

 of their body beyond the aperture of the sheath, and throwing the extended portion 

 into various graceful curves. On the slightest disturbance the body is withdrawn to 

 the bottom of its sheath, and contracted into a small ovate mass. In demonstration 

 of the non-permanent character of the attachment of the animalcule to the bottom of 

 its domicile, an example was observed on one occasion to vacate it and to 

 wander off in quest probably of a more productive feeding ground. In addition to 



