80 The Ohio Journal of Science [Vol. XIX, No. 1, 



stricted at each floor plate and expanded between floor plates 

 around the whole central ring. If one were to make a guess, 

 the intestine may have turned in a counter-clockwise direction 

 (oral orientation) to the left in each photograph and with four 

 inter-ambulacral enlargements may have reached the anal 

 pyramid at a point very close to where the intestine left the 

 posterior inter-radial space. 



Summary and Conclusions. 



• 1. Agelacrinites was probably somewhat motile, at least 

 able to adapt its skeleton to its surroundings. 



2. The peripheral rim may have been extensible. 



a. Evidence from the downward dropping of the inner rim 

 plates. 



b. The great redundancy of the large plates in some of the 

 species for simple support. 



c. Processes, probably for muscle attachment, on the 

 aboral side of the most of the rim plates. 



3. The animals in the Lawshe colony were probably 

 sexually mature the second season (by analogy from the star 

 fish). 



4. They breathed by muscular protraction, extension and 

 retraction of the anal pyramid, getting oxygen by rectal respira- 

 tion. 



5. The cover plates are variable in their arrangement, the 

 primitive condition being a single row on either side of the 

 brachial groove and the most complex a double row, an outer 

 large row and alternating with these an inner, small row on 

 either side of the arm. Transitions between these two con- 

 ditions are shown. 



6. There is a hydropore in the posterior inter radius near 

 the posterior peristomial plate and near arm 5. 



. 7. There are passages between the bases of the cover plates 

 at their aboral ends which probably have to do with a water- 

 vascular system. 



8. The peristomial plates are derived from the primitive 

 cover plates, and in the case of the posterior peristomial plate 

 at least also from the primitive inter-ambulacral plates by a 

 greater or less amount of fusion. Streptaster furnishes the most 

 primitive condition of peristome. 



