JURASSIC. 



81 



Fig. 19. — Restoration of Rhizostoinites, seen from below, after Brandt. The relative dimensions were taken into 

 account so far as possible. For the purpose of more accurate topographic orientation, there were drawn at the edge of the 

 umbrella, besides the 128 edge lobes, also the 16 rays in which the radial canals terminated, in analogy with living forms. 

 For the same reason also the position of 8 marginal bodies and of the circular canal was hypothetically indicated. In the 

 middle of t lie drawing the peduncles, and the mouth disk produced by their blending, were introduced. The mouth disk sends 

 out 8 arms, which have been drawn as if cut off at their base. On the mouth disk lies the mouth cross, whose secondary arms 

 continue on the oral edges of the arms. Dotted lines indicate the lids of the genital cavities, and of the ccelenteric central 

 cavity. 



A. Dome of the disk (umbrella). 



B. Mouth disk (stem). 



C. Its peduncles, or roots. 



D. Base of the peduncles. 

 !■'. Edge of disk. 



F, F l . Peripheral zone of disk (umbrella). 



H. Kidney-shaped plates (lids of the genital cavities). 



L. Mouth arms. 



11'. Four main rays. 



11-. Four intermediate rays. 



R •. Eight rays of lower rank. 



a. Center of mouth disk and central month rudiment. 



b. Primary arms of the mouth cross. 



c. Secondary arms of the same. 



d. e. Isosceles triangles with the mouth cross. 

 /. Ccelenteric central cavity, 



h. lioundary of the kidney-shaped plates (lids of the genital cavities) and in part of the 



central cavity. 

 i. Oval windows (entrances to the genital cavities). 



HON XXX li 



