Nov., 1918] Structure of A gelacrinites and Streptaster 85 



Plate VII. 



(All figures are camera drawings and are X 8.) 



Fig. 38. Agelacrinites aiistini var. lawshe, minute form aboral view. All the plates 

 distinguishable on the aboral side are outlined. The substomial cham- 

 ber and peristomial ring of modified floor plates are distinct. No other 

 flooring plates are separable. 



Fig. 39. Agelacrinites austini var. lawshe, aboral view showing substomial cham- 

 ber, peristomial flooring plates and one additional flooring plate of 

 food grooves 1, 2 and 5. The location of the anal pyramid is indistinctly- 

 indicated. 



Fig. 40. Agelacrintes austini, var. lawshe, aboral view. This shows food grooves 

 with two flooring plates in addition to the peristomial ring of modified 

 plates. The plate next the modified flooring plate on both food grooves 

 1 and 2 shows it double origin by a groove dividing it into proximal and 

 distal halves. 



Fig. 41. Agelacrinites austini, var. lawshe, aboral view medium sized specimen, all 

 plates drawn which were distinguishable. The peristomial ring is 

 shown open toward the anal pyramid, and with a triangular plate which 

 is the downward projection of oral plate P, and under several of the 

 flooring plates in food groove 1, the location is indicated of the round 

 pores which lead to the oral side of the plate and therefore to the food 

 groove. 



Fig. 42. As,ehicrinites austini, var. lawshe, aboral view. Specimen shows all plates 

 distinguishable. There are three flooring plates shown in the food 

 grooves 1 and 5, while the others are less complete. 



Fig. 43. View of the flooring plates and slipped over bases of the covering plates 

 of one food groove of a specimen of A. austini var. lawshe, showing 

 the grooves between the covering plates leading out of visceral space. 



Fig. 43. A is a similar view of a small portion of another food groove. 



Fig. 44. The substomial chamber and beginning of food grooves in another spec- 

 imen of A. austini var. lawshe. The aboral projection of plate P is dis- 

 tinct and also an unmarked plate at the end of groove 5 which msiy be 

 the peristomial plate V displaced. 



Fig. 45. Oral view of the food grooves and plates of a specimen of A . pileus, show- 

 ing the trimeric arrangement of food grooves disguised by the separa- 

 tion of 1 and 2 and of 4 and 5. 



Fig. 46. A section through the plates of the "rim" of A. cincinnatiensis to show 

 the great number of these plates and the way they have dropped 

 together. 



Plate VIII. 



Fig. 47. Oral view of Streptaster vorticellatiis showing the peristomial plates, cover 



plates and a few of the minute inter radials in inter space 4-5. 

 Fig. 48. Aboral view of Streptaster, showing the substomial chamber region and 



a large mass not separable into plates in the region of the 1-5 inter-radial 



space in which the anal pyramid is located. 

 Fig. 4n. Two cover plates of A. rectiradiatus. 



Fig. 50. Oral and end views of a flooring plate of A. austini var. lawshe. 

 Fig. 50A. Oral view of food grooves of A. austini, showing the alternation of 



large and small covering plates. 

 Fig. 51. Oral view of two floor plates of A. cincinnatiensis. 

 Fig. 51 A. Oral view of food grooves of A. ciiicinnatiensis, showing the covering of 



all but the ends of the inner smaller row of cover plates by the outer 



larger plates. 

 Fig. 51B. End view of open food groove showing the inner covering plates dotted 



in position. Also end view of one large covering plate showing one 



small plate and the groove in which it lies. 



