EXPLANATION OF THE PLATES. 135 



Fig. 4, Same as Fig. 2, only denuded of spines to show the plates of the actinal surface supporting 



them. 

 Fi"-. 5. Lono'itudinal section through the median line of the ambulacral furrow. 



All Figures natural size. 



This species is fjeneriiHy, on the abactinul side, a dirty orange yellow, passing into red ; more j-ellowish and lighter in 

 shade on the actinal surface. 



PLATE XVI TL 

 Cribrella sanguinolenta. 



Fig. 1. Seen from the ahactinal side, to show the minute spines covering the whole disk and arms. 



Fig. 2. Fig. 1, seen from the actinal side. 



Fig. 3. Enlarged view of spines round the actinostome and base of the arms. 



Fig. 4. Actinal view ; specimen denuded of its spines to show the close system of limestone plates form- 

 ing the actinal surface. 



Fig. 5. Interior view of the ahactinal surface, showing its close reticulation. 



Fig. 6. Longitudinal section across the central line of the ambulacral furrow, somewhat enlarged. 



Fig. 7. Interior view of the ambulacral system of one of the arms and its central connection, somewhat 

 enlarged. 



Figures 3, 6, 7 are somewhat enlarged ; all others, natural size. 



This species varies in color from brilliant orange-yellow to dark purple or dull violet. 



PLATE XIX. 



ASTROPECTEN ARTICULATUS. 



Dried specimen, from the ahactinal side. 

 Fig. 1, seen from the actinal side. 

 Ahactinal view of denuded specimen. 

 Actinal view of denuded specimen. 



Interior view of actinal floor, showing ambulacral system, the interbrachial arches, the connection 

 of ambulacra round the actinostome. 



Interior view of the ahactinal surface. 



Actinal region of sjiecimen somewhat larger than Fig. 4. 



Longitudinal section through arm, showing the great thickness of the marginal plates. 



All Figures are natural size. 



The marginal plates are of a light brown color with darker edges; the ahactinal surface of nearly the saw shade, some- 

 what lighter than the plates. The color is sometimes arranged in darker rectangular patches along the edge of the arms 

 on the ahactinal side. The marginal plates are also bright yellow, enclosing a violet ahactinal surface. 



PLATE XX. 



LUIUIA CLATHRATA. 

 Fig. 1. Ahactinal view from life. 



Fig. 2. Same, seen from the actinal side, showing the two rows of pointed tentacles. 

 Fig. 3. Same view as Fig. 1, denuded specimen. 

 Fig. 4. Preparation showing the plates of the actinal surface. 

 Fig. 5. Interior view of actinal floor, showing ambulacral system and mode of connection round actinal 



opening. 

 Fig. 6. Interior view of ahactinal surface. 

 Fig. 7. Actinal view of central part of disk, with tentacles contracted, showing the spines along the edge 



of ambulacral furrows and at their junction. 

 Fi2. 8. Longitudinal section of arm. 



