37 



sutures are gaping. A sinylo, rouiuled brachial supports upon 

 the upper sloping sides in each radial series, the free arms. 

 These brachials are contracted in the middle part and of unequal 

 length; the one opposite the azygous area is the longer, the two 

 adjacent are the shorter and the other two have an intermediate 

 length. There are only ten arms in this species; they are short 

 though composed of rather long, cuneiform, alternately projecting 

 plates. Each projecting joint bears a large, tapering, long joiuted 

 pinnule, which gives to the arms a rough geniculated aspect. 



The azygous area is covered with the same number of plates 

 which are arranged in the same order that they occur in 

 P. maccdbei. The difference between the two is that in this species 

 the ai-ea is proportionally narrower. 



We have three specimens of this species which are free ( and 

 accidentally the best one is not illustrated) beside the one 

 figured on P. maccabci, and they all bear the same propor- 

 tions as to size of calyx and arms and size of the plates. 

 The calyx in this species is fully as large as it is in P. maccabci, 

 though slightly differing in form, the arms and pinnules are as 

 coarse, but the arms have not more than two-thirds the length. 

 The question then arises whether tiie minor differences which may 

 be seen in the illustrations and the discriptions, coupled with the 

 wider azygous area and longer arms in P. maccabci, are sufficient 

 to distinguish species. One cannot be the young of theother unless 

 age widened the azygous area and lengthened the arms without 

 increasing the size of the plates, which is contrary to what we 

 know of these animals. P. maccabci is graceful in its form and 

 is not abnormal. Possibly the difference between the two should 

 be regarded as of specific value, but we have not regarded it as of 

 more than varietal importance. 



Found in the Kinderhook Group, at LeGrand, Iowa, and now 

 in the collection of Wm. F. E. Gurley. 



ZEACKINUS SALEMENSIS, n. sp. 



Plate III, Fig. 17, lateral view, azygous area on the left. 

 Our specimen is on a slab and the ray opposite the azygous 

 area is not exposed. The species is of medium size. Calyx basin- 

 shaped below the summit of the first radials and subpentagonal 

 in outline in the superior part, deeply concave below; sutures 

 distinct, surface granular. 



