6 1 2 ORDER HETEROTRICHA. 



were obtained by him from the neighbourhood of Stourbridge, Worcestershire, 

 attached to the leaves and stems of Anacharis alsmastrum. In one of the sketches 

 forwarded two examples are affixed to the rigid footstalk of a large Epistylis. 

 Although Stein * failed to detect in the examples examined by him the presence of 

 fine vibratile cilia on the general cuticular surface, he reports the existence, towards 

 the anterior extremity, of fine, scattered, hair-like setae, which appear to assist in 

 maintaining the animalcule in its extended state, and are apparently identical in 

 character with the similar structures present in certain species of Stentor and 

 Chcetospira. The record of the existence of these setae must be accepted as addi- 

 tional and important evidence in support of the Heterotrichous affinities of the 

 genus Tintinnidium and its allies, as advocated in this volume. 



Tintinnidimn semiciliatus, Sterki sp. Pl. XXXI. Figs. 6 and 7. 



Lorica subcylindrical, mucilaginous, flocculent and semi-opaque, through 

 the more or less abundant incorporation of vegetable debris, about three 

 times as long as broad ; enclosed animalcule conical or pyriform, truncate 

 and widest anteriorly, tapering posteriorly, and there continued in the form 

 of a slender, retractile pedicle, which equals the body in length and attaches 

 it to the bottom of the lorica ; cilia of the adoral wreath very large 

 and stout, flattened or lamellate, apparently pectinate at their distal 

 extremities ; the peristome-border enclosing an inner circlet of shorter and 

 finer simple cilia ; cuticular cilia limited to the anterior region of the body ; 

 oral cleft conspicuous, infundibuliform, produced backwards to a distance of 

 about one-third of the length of the entire body, associated with a movable 

 lip- or tongue-like organ ; contractile vesicle single, spherical, situated near 

 the termination of the oral cleft ; endoplast ovate, with a posteriorly 

 enclosed endoplastule, located on the opposite side and a little posterior to 

 the contractile vesicle ; adoral cilia only, during full extension, projecting 

 beyond the surface of the lorica. Length of body without the pedicle or 

 adoral cilia 1-625" to 1-416". Hab. — Fresh water, attached to Confervcs. 



This species is referred by Sterki | to the genus Tintinnus ; its distinctness 

 from Tintitmus (Tintinnidium) fluviatilis being, as he maintains, manifested in the 

 limited anterior distribution of the cuticular cilia, and in the peculiar character of 

 those forming the adoral wreath. These last-named appendages, according to 

 Sterki, are not simply cirrose, as with most ordinary Heterotricha, but are flattened 

 and lamellate, and thus coincide in structure with the so-called "membranellas," of 

 which, in accordance with the investigations of this authority, the homologous adoral 

 system of the Oxytrichidae is composed. Like the corresponding appendages of this 

 last-named group, they are inserted basally deep within the substance of the cortex, and 

 are further complicated by being split up in a laciniate or pectinate manner at their 

 free or distal end. Such a pectinate aspect is presented in the illustration reproduced 

 at PI. XXVIII. Fig. 7 ; but it would seem to be an open question whether or not 

 such delineation represents the optical aspect only of two or more concentric ciliary 

 circlets, and which, as they exist in many Peritrichous forms, have been frequently 

 depicted incorrectly as possessing a similar complex pectinate contour. Sterki, 

 nevertheless, is so satisfied as to the accuracy of his interpretation of these structures 

 as to give a drawing of an isolated pectinate cirrus, and reports that from fifteen to 

 twenty of these elements are associated in the complete series. While normally found 

 attached within their mucilaginous loricae, the animalcules of this species are capable 



* ' Infusionsthiere,' Abth. ii., 1867, p. 152. 



t ' Zeitschrift fiir Wissenschaftliche Zoologie,' Bd. xxxii., 1879. 



