190 



of the apical system. The same is true of all of the inter-ambulacra, 

 as far as can be determined. That part of ambulacrum V which is 

 near the edge is normal, and only the part near the center shows ab- 

 normal conditions, where only a few pores, and no sure traces of any 

 plates can be found. 



The apical system is also abnormal. Tlie madreporite is a large, 

 wart-like protuberance occupying almost the entire apical space. 

 During the treatment with potash this part was destroyed. Four 

 ocular plates are present, one in each of the ambulacra numbered I to 



<2nénr 



CUnlJ 



QmtW 



Fig. 3. Diagrams te show relation of the various systems of plates oc, ocular 

 plate; madr, madreporite. The lettering as in Figs. 1 and 2. 



IV (Figs. 1 and 3). No traces of genital plates or pores have been dis- 

 cernible at any time and I feel confident that they did not exist in 

 the specimen. 



On the ventral side (Fig. 2), the oral opening has moved towards 

 the anus about the same distance that the apical system has moved 

 away, the two giving one the impression of their having swung upon 

 some axis. The plates of the ventral side show no character worthy 

 of comment. 



In Fig. 3 I have plotted the arrangement of the ambulacra and 

 inter-ambulacra, together with that of the plates and pores in each, 



