76 



LUCEKNARIyE AND THEIR ALLIES. 



one-third greater in diameter tlian tliat of the sliaft, whereas in the adult it is three 

 times tluit of the shaft. We sliall not stop here to describe the mode of develop- 

 ment of the nascent tentacle, as that will be done in a future paragraph, but it will 

 not be amiss here to state simply that these organs originate as rounded papillae, elon- 

 gate into broad cylindrical shafts, and finally expand at the end into globose tips. 

 The breadth of a group is so great as to leave only a very narrow interval between it 

 and the anchors, so that we should say that, altogether, they occupy about two-fifths 

 of the circumference of the umbella. If now we add the tentacle-like anchors, 

 wliicli cover another third of the circumference, we shall see that so little marginal 

 space is left, and that, too, divided into no less than sixteen parts, that the umbella 

 appears to be fringed by an almost continuous corona of tentacles. 



152. T/ie Anchors (Jig. \2l,oc; 122, D; 123). — The distinctive characteristic of 

 these organs is not so far advanced in development as to obscure the tentacular 

 nature, and this is particularly noticeable on the proximal side, where scarcely a 

 trace of the colletocystigerous mass is to be seen; and the walls are identical in 

 their general features with those of the true tentacles. In point of size these 

 bodies, exclusive of the colletocystigerous mass (oc^), are about equal, in length and 

 breadth, to the tentacles. They have a similar thick shaft (oc'), and a well-defined 

 globular tip (oc'). As regards their attitude, they are more rigid, and remain nearly 

 fixed in a slightly bent form, inclined forward. The already large development of 

 the outer wall, into a colletocystigerous cushion (oc^), gives the anchor a still more 

 strongly bent figure, on the distal side, and in fact makes it appear as if it were 

 humped. The greater portion of the colletocystigerous mass lies on the distal side 

 of the organ, and extends a little more than two-tliirds of the way to the globose 

 tip. At the sides (fig. 121) it is nearly as thick as on the distal face, and thins 

 out all around as it stretches toward the base and the proximal side of the shaft. 

 Since, now, the tentacle-like portion has a tapering form, and expands at the base, 

 passing gradually, as far as outline is concerned, into the umbellar margin, and the 

 colletocystigerous layer thins out in the same direction, the tendencies of the two 

 are mutually counteracted, and the combined parts present the appearance in front 

 (fig. 121) of a broad projection with parallel sides, supporting a very short, globe- 

 tipped tentacle in a sinus at its end. 



152*. The Chondrophys (fig. 123, c).— Of the gelatiniform layers we have but a 

 word or two to say, and that only in reference to the ehondrophys. The forma- 

 tion of tins layer, in all probability, begins long before the time at which we have 

 found it, as at this period it is already very thick in tlie umbella, at least five or 

 six times thicker than the outer wall. 



§ 21. A Specimen ^^^ of an inch across the Umhella (PI. ii.figs. 20, 21 ; PI. x,». 



124 to 129). 



153. At this age the chief point of interest centres in the incipient reproductive 

 organs {fig. 20, X). Tlie stage previous to this might well be designated as the 

 proxhrn-ovullne stage, and the one in which the reproductive organs originate, 

 develop, and perform their functions might be denominated the adult stage. At 



