OF WESTERN SIND. 35] 



on the anterior suture. The twelfth plate is larger than those immediately anterior to 

 it, and the others, which are of higher number, increase in size until the crossing of 

 the peripetalous fasciole. The ornamentation of the ambulacral plates after the second 

 pair is very simple. In well-preserved specimens there are always distant granules to be 

 seen, which become rather crowded near the interradia. In some specimens there are 

 linear depressions on the plates, one to each, and there are two minute granules in each. 



The peristome is crescent-shaped in front and at the sides, and the posterior lip 

 projects forwards and downwards, and is at a lower level than the rest of the mouth, the 

 whole being within a concavity in the anterior third of the actinal surface. 



The peripetalous fasciole is narrow and continuous. It crosses the posterior inter- 

 radium about halfway between the end of the posterior petals and the edge over the 

 anus, curves towards and round the end of the posterior petals, and passes forwards 

 with a slight convexity towards the ambitus, to reach the an tero -lateral ambulacra at 

 some little distance from the termination of the large pairs of pores. During this 

 last part of its course the fasciole bounds externally an area on which are four rows 

 of large sunken tubercles, the outer row being the longest as a rule. From this spot 

 the fasciole passes with a slight curve to the anterior groove, and crossing this at 

 some distance from the margin of the test, meets its fellow of the opposite side. 

 In this part of its course the fasciole bounds a tuberculate area where four more or 

 less developed rows are seen. 



The internal fasciole is also narrow, and is usually situated in a very shallow 

 groove ; but sometimes this becomes indistinct. Posteriorly this fasciole forms a 

 wide angle between the closely approximated poriferous zones of the posterior ambu- 

 lacra (zones h of no. V. and a of no. I.). It crosses these poriferous zones, dividing 

 the large from the minute pairs, at about the seventh interradial plate from the 

 apex. The fasciole then passes forwards and outwards to reach the outer poriferous 

 zones of the posterior ambulacra; thence it pursues the same line, and shortly 

 crosses the posterior poriferous zones of the antero-lateral ambulacra, at spots on a 

 line drawn across the apical system. In both of the approximated zones of the 

 ambulacra there are some pores separated from their fellows. From these places the 

 fasciole passes, being rather narrower, forwards. It crosses the antero-lateral ambu- 

 lacra and in front of the first large sunken tubercle of the anterior interradia. Passing 

 a little further to the front and nearly to the second tubercle the fasciole crosses the 

 anterior groove, the broad keels on either side of it and the narrow odd ambulacrum on 

 its floor. This part of the fasciole is narrow and is curved forwards. 



The subanal fasciole is well marked and broad, and environs a more or less uneven 

 surface irregularly semicircular in shape. The convexity of the path of this fasciole 

 is forwards to the keel on the actinal surface at the junction of the sternum and epi- 

 sternum. The band is limited posteriorly by the plain surface beneath the anal opening. 

 The fasciole crosses the posterior ambulacra and includes no less than seven plates of 

 the inner zones, and these form an angular surface on both sides of the episternum 

 and succeeding interradial plates. 



