DESCRIPTION OF THE PLATES. 125 



although the colletoeystophoric pail (a^) is cousklerably dovclopoJ. At v/i' is tlio niai-giii of the mus- 

 cuhu- layer, (magnified 175 diam.). 



Fig. 31. Profile view of fig. 30, showing the front face (a") to be still purely tentacular. 



Fig. 32. Normal development of an anchor, seen in profile, from fig. 29 (mag. ITo diara.). Tlie 

 colletoeystophoric pad {a) is considerably- more advanced than in figs. 30, 31. 



Fig. 33. One of the oldest tentacles of fig. 20 (§ 22), fully expanded to show the proportionate 

 thickness of the walls and the relative size of the globular tip (ncmatocystophore) (t"). The neck 

 (ij>') at the base of 4>' is well marked (mag. ITS diam.). 



Fig. 34. Young tentacle whose ncmatocystophore {'p') is uot yet distinct from the shaft (t')- ('i"^,!^- 

 115 diam.). 



Fig. 35. Abnormal development of colletocysts {a) on a young tentacle (mag. 00 diam,). 



Fig. 30. Part of the shaft of a tentacle while contracted into a zigzag (mag. 00 diam). 



Fig. 37. Magnified (5 diam.) longitudinal section of adult along two diverse lines, on nearly oppo- 

 site sides. The section on the left passes through a group of tentacles Qf), a genital half (C), and 

 through the proboscis (p) near one of its corners, and thence backward along the peduncle, just this 

 side of a canal (r') to its posterior end. The section on the right, passing through a colletocysto- 

 phore (a), extends along the midline of a partition (4--) and of a flat side of the proboscis (p), thence 

 along a muscular cord (/•-) in the post-bueoal region, and contiuues to follow it (r) into the peduncle 

 to its expanded posterior end (/•'). The peduncular canal (t*) on this side is seen in the distance, 

 beyond the muscular cord (r). The section on the left exposes the umbcllar cavity (V) !is well as 

 the digituli (ij) festooned about the po.st-buecal cavity (4."). 



PLATE IV. Flii^ires 33 to 51. 



Figs. 38, 39, 40. Abnormal conditions of the ncmatocystophore of tentacles (mag. 00 diam.). 



Fig. 41. Kormal condition of a fully developed tentacle, showing the depressed end of the nema- 

 tocystophore (GO diam.). 



Fig. 42. Fully extended tentacle of a two-thirds grown individual. It very commonly assumes 

 the curved attitude here represented (GO diam.). 



Fig. 43. End of a young, but fully formed tentacle, principally to display its ribbed appearance, 

 and the bristling tactile bodies and the nematocysts which dot the globular tip (r) (175 diam.). 



Fig. 44. Different view of same as fig. 43, .showing the end of the nematocystophore (t'), but the 

 shaft curved around into profile, and drawn to exhibit the zigzag position of the innermost wall (i^), 

 moving apparenlUj free within the outer wall. The great plasticity and extensibility of the inter- 

 vening layer (chondromyoi)lax) (ii') allows these two walls to slide over each other to a great extent, 

 and apparently, with a low power, as if without any iutervening connective tissue (175 diam.). 



Fig. 45. (20 diam.). Interior of the region about a colletocystophore to expose its entrance 

 (a"). The oral side (Q of the umbella is thrown upward. The margin of the pigment coloring of 

 the aboral side (/3) is well marked along the edge of the marginal muscle (m')- 



Fig. 40 (GO diam.). Profile of the posterior end of a peduncular muscle ()•) and its extension 

 (»•') toward the middle of the adherent disk (y). 



Fig. 47 (CO diam.). Section of a colletocystophore and the adjoining umbellar margin, including 

 a portion of the distal end of a partition next an intcrcamcral passage-way (V), showing the relative 

 thickness and position of the layers, and exposing the interior cavity. 



Fig. 47'' (00 diam.). Continuation of the section above figured {fiig. 47) into the region about 

 the base (p^) of the proboscis ; principally to show the relation of the layers of the nnibella and the 

 proboscis and to expose the peduncular muscle (y), where it passes forward into the proximal end 

 (4.^) of the partition, and thence diverges into the i)roboscis (at m^) and into the umbella (at )?t*). 



Fig. 48 (350 diam.). A young tentacle contracted ; displaying, in a sectional view, the relative 

 position, thickness, and the elementary structure of the layers, and the imbedded nematocysts (Z). 



Fig. 49 (GO diam.). Interior view of the peduncular muscle (y) at the point where it i)lunges 

 forward, narrows (y') a little, and then expands into a flattened layer ()n) in the circumoral area. 

 (Compare this with fig. 47".) 



