NOTES ON ECHINODEEM MOEPHOLOGY. 7 



ing species the basals are still larger and the proximal inter- 

 brachial plates are in immediate contact with them, so that the 

 radial primaries do not meet one another at all. 



Ophiactis cuspidaU. I Ophiopbolis japonica. 



Ophioglypha fasciculata, 

 „ imbecillis. 



,, lacazei. 



„ tenera. 



Ophiolepis januarii. 



Ophiomastus texturatus. 



Ophiozoua autillarum (PI. I, 

 fig. 6). 

 ,, depressa. 



„ insularia. 



Ophiura albida, 

 „ squamosa. 



This separation of the radial primaries also occurs in 

 Ophioglypha lapidaria, Ophiomusium granosura, and 

 O. flabellum. (PI. I, figs. 3, 4, 7). In all these three 

 species the basals (3) and the radials (4) are about equal to 

 one another, while in the last named they are also of nearly the 

 same size as the dorsocentral (1). The ''primary"^ plates 

 immediately surrounding the dorsocentral are therefore inter- 

 radial, and not opposite the arm-bases as " primaries " usually 

 are. This difference is left unnoticed by Lyman, who speaks 

 merely of a " central primary plate surrounded by live others " 

 in O. lapidaria, and does not mention the real radial primaries 

 (4) at all. The apical plates of the other two species are 

 described as follows : — 



Ophiomusium granosum (PI. I, fig. 7). ''In centre of 

 upper surface of disc is a large pentagonal primary plate, 

 surrounded by five others, quadrangular, and connected with 

 the radial shields by five rudely triangular pieces; in each 

 interbrachial space above are two quadrangular plates besides 

 that of the margin.^' 



O. flabellum (PI. I, fig. 3). "The central primary is 

 pentagonal, surrounded by a row of angular plates, of nearly 

 equal size; outside this row, in each interbrachial space, is 

 another angular plate separating the inner ends of the rather 

 long, closely-joined radial shields.^' 



In both these descriptions the basals (3) or angular inter- 

 radial plates immediately next the dorsocentral (1) are referred 

 to as " primaries ; '' while the true radial primaries (4), homolo- 



