UEPOUT ON THE oPiilUliolDi'A, 3(}7 



space on each side. Below is the arm bone, 

 with its under (h) and side arm plates (i) bear- 

 ing the spines. On either side passes up the 

 genital opening (no) into the bursa with its 

 folded wall which closely follows the pleated 

 digestive cavity (St, St), with its thick (hepatic, 

 or epthclial ?) layer. One little lobe (St') is 

 pushed into the bursa and cut by the section. 

 The wall of the bursa is a thin continuation 

 of the disk wall ; hence its tendency to calcify. 

 In this species it has fine scales of lime in its 

 substance. In the bursal folds lies a young 

 (Y) ; and two embryos (Y/) are seen in side 

 pouches. To the right of the upper arm of 

 the young may be seen a section of a tip of 

 another arm, bent round in a fold of the bursa ; 

 genital plate (o) ; tentacle (r) ; radial shields 

 cut through (/,/). 

 Fig. 9. Ophiacantha vivipara, Ljn., ? , 3 f-°. Liver-like cells from the very thick wall 



of the digestive cavity. This layer seems to be 

 the one spoken of by Ludwig as epithelial. 



PLATE XL VII. 



Fig. 1. Astrophyton exiguum, Agas., f. Disk from above, with two arms. 



,, 2. Ophioglypha hexactis, E. A. Smith, $ , f. Disk with its roof removed and seen 

 from above. Above the digestive cavity (St, St), which is ruptured in 

 the middle, lie the genital bursas (88), near which may be seen four young 

 ones in several stages of growth. Each is contained in a translucent 

 membranous sac, which is ruptured over the largest. 



„ 3. Ophiocoma scolopendrina, Agas., $ , f. Vertical section of the disk passing 

 through one arm (Am) and the opposite interbrachial space: digestive 

 cavity (St), whose upper wall adheres to the roof of the disk ; jaw (c) ; 

 section of mouth frame (f) ; genital plate (o) ; genital bursa (8) ; con- 

 voluted spermaries (8',8') 4 



,, 4. Ophiothrix longipeda, Miill. & Ti\, ? , J. Vertical section of the disk passinc 

 through one arm (Am) and the edge of the opposite interbrachial space. 

 including a slice of an arm (Am). The spaces over and beside the arms 



