238 NEW YORK STATE MUSEUM 



boundaries between neighboring plates. In other words, two sutures 

 meet to form an angle at a point which lies in one extremity of a 

 third suture. Plate 6 figures i and 2, show that our radianal forms 

 no exception to the law though it has a rather rounded outline which 

 at a is so marked and further intensified by the prominent middle 

 epithecal canal from r.post.B as to give it the appearance of possess- 

 ing a fifth angle. The plate is, however, essentially quadrangular, 

 as in Porocrinus, and was truly so in its early neanic stages. Bath- 

 er's figure, already cited, makes the projection at a one of the angles 

 of the plate and places additional ones midway of each of the other 

 three sutures bounding the plate. Not one of the angles so drawn 

 meets a third suture in the figure he has used. In addition to these 

 erroneously placed angles, the true upper and lower angles of the 

 plate were recognized, thus making it hexagonal. The angles at the 

 junction of r.post.R with r.post.B and that at the junction of x and 

 post.B were not seen. The mounting process has, however, made 

 these clearly visible in the untouched photograph used for plate 6, 

 figure 2. The rounded surface of the plate makes the sutures 

 appear as meridians viewed from the side. With the sutures in the 

 center of the field of view they show more nearly as straight lines 

 and, with the exception of the abberant suture next r.post.B, they 

 have been so represented in text figure 4. Even this suture becomes 

 a nearly straight line when viewed as in text figure 5. 



The epithecal canal passing on to this plate from r.post.B has had 

 its covering and a good portion of the sides removed. The floor of 

 this canal may be distinctly seen in plate 6, figure 2, lying to the 

 right of a wide portion of its left wall. Where it is broken or cut 

 oft' at the radianal end, there is a black patch that represents a limon- 

 ite mud-filled basin which occupied this left canal wall and opened 

 into the canal itself by a smaller pore. This same figure also shows 

 a series of such limonite mud-lined or filled basins along the left 

 side of the strong exothecal canal wdiich runs from r.post.B over 

 r.post.R. The pit shown in plate 6 figure 2 ^ is so definite, so well 

 lined with limonite-colored mud and afterward filled with calcite 

 that it challenges attention. Many similar pits are suggestive of 

 protected side water pores opening into the canals, but the structures 

 are so irregular in arrange rent and so large a portion of them may 

 be due to differential solution or other erosive process that they will 

 be dismissed with this mention. Another very definite structure that 

 is perhaps connected with respiration may also be mentioned hero. 

 It is found close to the plate angles and is in the form of two very 



