150 
area which is otherwise sharply limited, fairly broad, with a distinet 
corner at each horizontal suture. In the ambulacra (Fig 2 ) which 
are flush with the test, the naked, sunken median area is quite 
narrow, but sharply limited; on the oral side lt is restneted to a 
small, but distinet, groove at each horizontal suture. Each plate 
carries a small tubercle at the lower corner inside the primary 
one, which latter is not very prominent. The pores are obhque, 
separated by an elevated wall. 
The apical system (Fig. 3) is half h. d„ flat. The oculars are 
exsert; however in specimen a. Oc. III, and in specimen b. Oc. IV 
Fig. 3. Apical system of Ogmocidaris Benliami. 4 /i. Fig. 4 
Ogmocidaris Benhami. 8 /i. 
Oral radioles of 
touches the periproct, while in both Oc. I very nearly-reaches.it. 
The genital plates have a nearly straight outer edge, the outline 
of the whole apical system is thus almost circular. The female 
genital pores are large, close to the outer edge of the plate. (Both 
specimens are females). The periproct is small, consisting of few 
plates only. The whole of the apical system closely covered with 
tubercles, excepting a fairly broad inner edge of the genital plates, 
which remains bare. The peristome is covered only with few plates, 
v j z . 4 _ 5 sparsely tuberculated ambulacral plates and 2 3 small, 
weak interambulacral plates, which are widely exeluded from the 
mouth edge. The structure of the peristome upon the whole recalls 
that of the genus Aporocidaris. 
