GENUS VORTICELLA. 689 



of the expanded body or to the ornamentation of the cuticular surface of this exceed- 

 ingly elegant form, although of the two Mr. Tatem's delineations are by far the more 

 characteristic and complete. According to this last-named authority, it is by no means 

 an uncommon form, he having obtained it from various widely different localities. 

 The present author has also had the good fortune to meet with this very distinct type 

 on several occasions, receiving it first, in March 1874, growing upon Myriophyllinn in 

 company with Epistylis grandis and other animalcules, through Mr. Thomas Bolton, 

 from the neighbourhood of Stourbridge, Worcestershire, and has more recently obtained 

 it in the neighbourhood of Ashby-de-Ia-Zouch. From the notes and sketches made 

 at these times, it is now found possible to fill up certain of the very extensive 

 lacunae left by its original describers. In the first place, the beading of the cuticular 

 surface has been demonstrated by examination with a high magnifying power to be 

 much more even, closely set, and generally distributed than is indicated by either 

 Mr. Tatem or De Fromentel. The symmetrically annular disposition of these bead- 

 like prominences, and their correspondence in that respect with the transverse 

 cuticular striae of various other species, is recognized by the former writer, but he has 

 at the same time represented the separate beads as much more distinctly isolated 

 from one another than is actually the case, while the elevated and in certain aspects 

 dome-like ciliary disc is, in accordance with Mr. Tatem's drawing, entirely smooth 

 and deficient in the ornamentation that distinguishes the remaining portion. The 

 surface of the ciliary disc was found by the author to be similarly decorated, the 

 hemispherical elevations being, indeed, of slightly larger size than on the walls of 

 the body. This cuticular ornamentation, however, attains its most conspicuous 

 development on the surface of the peristome-border, in which region the bead-like 

 markings are quite twice the size of those of the subjacent area. When expanded to 

 its full extent the peristome-border is everted and revolute to an extent apparently 

 unobserved by its previous biographers, the contour of the body also assuming at 

 such times a more elongate, conoidal outline. Between this conical shape and the 

 perfectly spheroidal one assumed in its contracted state, every gradational contour 

 may be exhibited. De Fromentel cites as a special character of this type the zig- 

 zag, or more correctly spiral, disposition of the contractile muscular cord within the 

 pedicle. This is, however, common to all Vorticellce, but in this type, on account of 

 its large size, is particularly prominent. For a similar reason, the continuation of 

 this cord up the walls of the body as distinct fibrillae is also clearly shown in this 

 species. About six or eight zooids usually made up the colonies of this species as 

 examined by the author ; in most instances a conspicuous but comparatively short 

 band-like endoplast was observed. 



Supplementary Species. 



The following Miillerian species are too insufficiently defined for inclusion 

 among the preceding series, their original diagnoses being however here reproduced 

 with a view to their possible rediscovery and more exhaustive description. 



Vorticella cyat/ii>ia, Miiller, PI. XLIX. Fig. 40. — Body crateriform, stalk spirally 

 retractile. Hab. Salt water preserved in glass vessels. 



The shape of the body of this species as figured by O. F. Miiller,* coincides 

 most nearly with that of Vorticella campanula or V. iiutans. The average length of 

 the pedicle is from three to four times that of the body. 



Vorticella annularis^ Miiller. PI. XXXIX. Figs. 27 and 28. — Body elongate- 

 conical, the anterior margin truncate, the distal end of the footstalk alone retractile, 

 this region thickened and smooth when extended, annulate when contracted. 

 Hab. Fresh water, attached to Planorbis sp. 



According to Miiller's figures and description of this species, the separate zooids 

 are of a very considerable size, being distinctly visible to the unaided eye, and 

 measuring in length the i-joth or even the 1-2 5th of an English inch. Excepting 

 for their large size and the fact that each zooid in the colony he delineates is 



* ' Zoologia Danica,' 1788. 

 VOL. II. 



