MOIRA CLOTHO. „ 215 



corresponding to the posterior interambulacral areas. The narrow polygo- 

 nal genital plates are deeply notched to receive the four lateral oculars 

 (PI. 109, figs. 2, 4, .5), the posterior pair cutting into the centre of the 

 genitals, the anterior pair being notched into the narrow extremity of 

 the genital plates ; they extend a short distance on each side of the anterior 

 ocular plates (PI. 109, figs. 4, 5). The right genital carries the madre- 

 porite, which covers the greater part of the plate adjoining the odd 

 interambulacrum (PL 109, fig. 4). The odd ocular plate fits into the inner 

 curved edge of the genital plates at their junction. 



Seen from the interior (PI. 109, fig. 5) there is no trace of the suture of 

 the anterior genitals, and only a mere line to indicate the junction between 

 the two genitals so well seen from the outside. The extension of the stone 

 canal on the right genital is very prominent (PI. 109, fig. ,5). 



The expansion of the ambulacra in the interior of the test has quite 

 hidden the abactinal anterior interambulacral plates. They are already quite 

 narrow when seen from the outside of the test (PI. 109, fig. 4), but when 

 seen from the interior (PI. 109, fig. 5) only two very slender plates are 

 visible in the space between the odd and the anterior ambulacra. It is 

 interesting to note that the central angular sutures are curved, following 

 more or less the general curve of the sunken ambulacral plates. 



The internal fasciole is very irregular in its development, often merely 

 marked by a bare space covered with most minute tubercles along the bevelled 

 edge of the petals where they join the ambulacra (PI. 109, fig. ..'), or with 

 intermittent tubercles apparently worn from an edge formerly well covered, 

 as is indicated on Plate 109, fig. 6, which represents the internal fasciole on 

 the edge of the petal of the third interambulacral plate from the genital 

 plate. 



When seen in profile (PI. 109, fig. 3) the anterior part of the test makes 

 a sharp indentation at the point where the anterior petals turn sharply 

 towards the apical system, near the point where the peripetalous fasciole 

 follows on both sides the edge of the anterior petals to their extremity. 

 Nearly from the same point on the anterior edge the fasciole strikes across 

 the test to the extremity of the odd anterior petal, where it crosses the odd 

 ambulacral area (PI. 109, fig. 2). The inner fasciole follows the edge of the 

 lateral petals, and the anterior part forms a part of the peripetalous fasciole 

 which branches off from the anterior petals and runs diagonally down the 

 side of the test towards the anal system. 



