664 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.39. 



EXPLANATION OF PLATES. 

 (All plates represent Hyalinothrix millespina.) 

 Plate 69. 

 Abactinal view of type, enlarged about 2^ times. 



Plate 70. 



A portion of actinal surface of type enlarged; int, actinal intermediate plates; 1-5, 

 the five series of actinal intermediate plates. The three plates of the fifth series 

 are marked with white spots, there being an unpaired plate, and one to each 

 ray; inf, inferomarginal, and sup, superomarginal plates. Between the two 

 white lines indicating these plates are seen the first superomarginals of each ray. 

 The lines in both cases point to the second plate of the series. 



Plate 71. 



Fig. 1. Abactinal plate from near base of ray, side view; X30. This is to give an 

 idea of the relative size of tabulum and spinelets; not all the latter are 

 shown, and most of these are represented somewhat too stout. 



2. Spinelets from abactinal plates; X70. 



3. The base and tip of a spinelet; X250. 



4. Abactinal plates from near base of ray and border of midradial area, seen from 



outside to show the tabula and papular areas, in which the one or two 

 papulae are not indicated; XIO. 



5. Abactinal plates from near base of ray and adjacent portion of disk, seen 



from inside; X 10. The plates to right are those of the radial area, those to 

 the left showing the more regular arrangement of the dorsolaterals. Pap- 

 ular areas shaded; s, position of interbrachial septum. 



6. An adambulacral plate from proximal half of ray; XIO. Not all the eub- 



ambulacral spinelets can be shown. 



7. Three ambulacral plates from near base of ray to show the lobes at lower end 



over-lapping the suture between the adambulacral plates; XIO. 



