Prof. H. J. Clark on Lucernaria. 27 



of the very obvious office of an auricle, I would propose the 

 name anchor for it. 



Were the above-mentioned features in the organism of Lucer- 

 naria alone to be taken into account, there could be no hesitation 

 in saying that this genus should be considered as the highest of 

 the class of Acalephse, because of its highly complicated and 

 specialized gelatiniform mass, the high grade and the peculiar 

 and distinctive grouping of its muscular system, the definite 

 and bilateral form of the genital organs, as well as their saccular 

 subdivision, the twofold nature and disposition of the prehensile 

 organs, the tentacles and anchors, — and, moreover, that it belongs 

 to an order separate from the other orders of Acalephse, because of 

 the typical elements of its genital saccules, which are altogether 

 different from either the Steganophthalmic or Gymnophthalmic 

 type of genitals — and also on account of the anchors, which 

 have no parallel in all the class of Acalephce. But there are 

 parts of the Lucernarian organism which are of a lower grade 

 than those of similar nature among the other Acalepha. I refer, 

 in the first place, to the Hydra-like form of Lucernaria, and its 



oval part of the shaft is endowed with three equidistant spiral rows of setae, 

 which number about a dozen in each row. The setae are comparatively 

 large, and in length equal two-thirds the broadest diameter of that part of 

 the shaft from which they project. Each row makes but one turn about 

 the shaft, and terminates as if in continuation of the angles of the trihedral 

 thread. There is not the least trace of setae or projections of any kind 

 upon the trihedral thread, but it continues, with a very gradual taper, 

 perfectly smooth, to the blunt termination. The angles of the thread 

 appear, at first glance, as if they might be spiral rows of setae ; but a most 

 careful and prolonged examination with one of Spencer's j-inch objectives 

 convinces me that they are truly the angles of a twisted trihedral filament. 

 The extent of the thread is from twenty to twenty-four times the length of 

 the cell. The other kind of nettling cell is much more simple in structure, 

 but yet more remarkable. The introverted shaft is very slender — in fact, 

 no larger than the rest of the thread ; it does not project into the axis of 

 the cylindrico-oval cell, but presses close to the side of the latter, and ex- 

 tends four-fifths of the way to its opposite end, and then, bending abruptly 

 upon itself, the thread passes with a long curved sweep nearly to the aper- 

 ture of the cell, from whence it again returns, with another long sweep, 

 which is repeated eight to ten times, until the inner face of the cell-wall 

 is lined by a close coil which winds lengthwise, instead of transversely as 

 it does in the other kind first described. When extended, the thread 

 is from twelve to fourteen times the length of the cell ; it oflPers not 

 the least s'gn of appendages of any kind, but is simply a smooth round 

 filament, of uniform thickness throughovit, except at the end, where it 

 tapers slightly and terminates in a blunt tip. The cell itself, when retro- 

 verted, is sensibly diminished in size, and narrows rapidly into the pro- 

 longed filamentary portion. It would seem to be perfectly incontestable 

 that, as the cell diminishes in size with the expulsion of the thread, it 

 forms the propelling power, and by the contraction of its wall forces its 

 contents outward. 



