MELICERTAD^E. 89 



Genus CONOCHILUS, Ehrenberg. 



GEN. CH. Cluster free- swimming, of several individuals, inhabiting coherent gela- 

 tinous tubes ; corona horse-shoe-shaped, transverse ; gap in the ciliary wreath ventral ; 

 buccal orifice on the corona, and towards its dorsal side ; dorsal antennae absent ; ' 

 ventral antennae obvious. 



Take a clay model of an CEcistes, and cut off the head by a transverse section through 

 the neck. Lift up the head, and reverse its position, placing the surface of the corona on 

 the decapitated trunk, so that the entrance to the buccal funnel may point towards the 

 centre of the dorsal surface. There will thus be obtained a rough representation of the 

 relative positions of the trunk, corona, and ciliary wreaths in Conochilus. Such a 

 violent alteration in the general plan of the Melicertadce might almost seem to entitle 

 Conochilus to a family by itself, but its affinities are so clearly with this group that it 

 may well remain here. 



On the surface of the corona, 2 close within its edge, and parallel to it, runs a groove, 

 which is broadest and deepest opposite to the dorsal surface, where it is confluent with 

 the entrance to the buccal funnel. The groove grows both narrower and shallower on 

 each side as it approaches the ventral surface, and ceases just before reaching a ventral 

 gap in the corona. 



The buccal funnel, except at its wide entrance, is covered by a sloping roof, formed 

 of the uplifted corona, which here rises into a kind of pent-house, notched at its apex. 

 The principal wreath runs round the outer edge of the groove, and is joined, at each side 

 of the ventral gap, by the secondary wreath. This latter fringes the groove's inner 

 edge ; and on reaching the buccal funnel, bends sharply back, rising up each edge of its 

 walls, till it has reached the notch described above ; so that in Conochilus, as in other 

 MelicertadcB, the entrance to the buccal orifice lies between the two wreaths, and is bor- 

 dered by the secondary one. 



The two known species differ considerably in their modes of clustering, and in their 

 antennae : they apparently closely resemble each other in other points, but only one 

 has been really studied, viz. C. volvox. 3 



C. VOLVOX, Ehrenberg. 

 (PI. VIII. fig. 8.) 



Conochilus volvox .... Ehrenberg, Die Infus. 1838, p. 393, Taf. xliii. fig. 8. 



,, ,,*.... Eichwald, Dritt. Nacht. z. Infus. Busslands, 1852, p. 520. 



, Cohn, Sieb. u. Roll. Zeits. Ed. xii. 1863, p. 197, with figs. 



Pritchard, Infusoria, 1861, p. 664, pi. xxv. 365-370. 



Megalotrocha volvox . . . Gosse, Popular Sci. Eev. vol. i. 1862, p. 491, pi. xxvi. figs.e,/. 



Conochilus volvox .... Davis, Hon. Micr. J. vol. xvi. 1876, p. 1, pi. cxliii. 



, Bedwell, J. Boy. Micr. Soc. vol. i. 1878, p. 176, pi. xi. 



Hudson, J. Eoy. Micr. Soc. vol. ii. 1879, p. 3, pi. ii. 



, Imhof, Zool. Anz. No. 147, 1883. 



1 Possibly very minute. 



2 Ehrenberg misunderstood the corona of C. volvox, and described it as surrounded with a single 

 wreath of cilia and bearing four papillae on its surface. He placed the buccal orifice on the ventral 

 side, where the ventral gap is ; and suggested that the four papillae might be a sort of upper lip to the 

 mouth, the edge of the disk itself being the lower one. Dr. Cohn, in his otherwise admirable paper 

 (loc. cit.), draws the buccal orifice on the ventral side, and wrongly places the antennas between it and 

 the dorsal surface. His conical protuberance over the antenna is also singularly out of shape and 

 proportion. The corona and antennae were first correctly described by Mr. Davis (Zoc. cit.), whose 

 observations I have repeatedly verified. 



3 Stroplwsphcera ismailoviensis (Poggenpohl, N. Mem. Mosc. t. x. 1876) is, I think, a Conochilus ; 

 with two short separate antennae lying between a pair of ventral hooks. 



