126 



DESCRirTION OF THE PLATES. 



Fin. 50 (GO tliam.). Sectional view of the region about the base of the proboscis (p), including 

 the post-buecal cavity {^'■) and a part of the peduncle. The muscles (r), right and left, are exposed, 

 and the canals (t") lie in the di.^tance, as well as one of the muscles (at r") in the post-buceal cavity. 

 In the umbella, vi is the expanded prolongation of r- each side of the partition (4.'). Compare 4^ 

 with the same in fig. iT. 



Fig. 51 (fiO diam.). Longitudinal section through two diagonally opposite tubes (r') at the pos- 

 terior end of the peduncle, showing the irregular passage-ways (t') in the region of the adherent disk. 



PLATE Y. Figures 52 to GO. 



Fig. 52 (T5 diam.). Transverse section of the peduncle to display the relative positions of the 

 muscular cords (>•) and the tubes (r"), as well as the arrangement of the fibrils of the chondrophys 

 {c\ &). 



Fig. 52" (T5 diam.). One of the muscles of the peduncle cut across, and lettered in reference to 

 the main subdivisions. 



Fig. 53 (1T5 diam.). Longitudinal section of one side of the proboscis of a young specimen 

 {fig. 84), with a portion of the circunioral area. At p' to p' is a face view of the innermost wall (/') 

 in the distance. 



Fig. 54 (100 diam.). Section, slightly varying in direction, through a group of tentacles, cutting 

 some (A, D) lengthwise, and opening the base of others (B, C), as well as exposing the interior of 

 some of the solid intertcntacular lobes («). The mouth (.s") of the genital sac (s) is always turned 

 toward th« proboscis, as drawn here. 



Fig. 55 (100 diam.). Outline view of the globular tip of a tentacle to show the terminal depres- 

 sion. 



Fig. 56 (100 diam.). Interior face-view of the region occupied by the intertcntacular lobes (;t) 

 and the entrances (<}>') of the tentacular cavities. 



Fig. 57 (470 diam.). The tissue and pigment granules about the entrance (if'") to the hollow of a 

 tentacle. 



Fig. 58 (175 diam.). Longitudinal section of the basal part of the tentacles, tentacular lobes, and 

 a part of the umbella. The circunioral Door (s) thrown up slightly so as to expose the inner face, 

 and the marginal muscle (?n'). From a very young animal (§ 22). 



Fig. 59 (175 diam.). A budding tentacle (Jmn fig. 58) with a part of the walls of a larger ten- 

 tacle (4>). 



Fig. GO (300 diam.). Sectional view of the base of a tentacle, intertcntacular lobe, and the adjoin- 

 ing aboral umbcllar margin. 



PLATE VI. Figiires Gl to 66. 



Fig. CI (100 diam.). Section across two extended corners of the umbella and the partition (4.-) 

 lying between them. The section across one of the corners is partially omitted, as it is an exact 

 duplicate of the other, reversed. The genital sacs (s) all open (s«), in one direction, into the umbcllar 

 camera (V). At 6« the chondromyoplax meets the chondrophys {(■') and breaks the continuity of 

 the innermost wall {i) of the camera;, and forms the bulk of the partition. 



Fig. C2 (100 diam.). Section across one corner of the umbella nearer its margin than in the 

 last, principally to show the considerable depth of the ridges (m', m^) of the muscular layer, and 

 the peculiar concavo-conve.x surface of contact of the circunioral (^ and aboral {?) floors of the 

 umbella, against the intervening muscular layer (!■'). 



Ftg. 63 (200 diam.). Section across an umbcllar partition (4.') and a part of the circumoral and 

 aboral floors near it, at a point nearer the proboscis than in figs. Gl and C2, including one of the 

 youngest genital sacs (s). 



Fig. 04 (200 diam.). Longitudinal section at the same point as fig. G3, cutting the partition M) 

 lengthwise. 



