LOWER HELDERBERG ROCKS. 100 



These fossils have become extremely rare, no specimens having been discovered 

 in many years past. 



Fig. 1. An individual preserving the body and greater portion of tlie arms, -with, several 



inches of the column. 

 Fig. 2. The body and lower part of the arms, showing the surface characters in a good 



degree of preservation. 

 Fig. 3. A specimen with arms, armlets, and tentacula nearly entire. 

 Fig. 4. Diagram illustrating the structure of the body and one arm to the second bifurcation 



of the brachial plates. 

 Fig. 4 a. Enlargement of a portion of an arm, showing the arrangement of plates and 



origin of armlets. 



Geological position and locality. In some shaly layers near the base of the Pen- 

 tamerus limestone of the Lower Helderberg group, Schoharie. 



Mariacrinns paucidactjlus (n. s.). 



Plate III. Fia. 5. 

 Body somewhat obconical, very gradually enlarging above. Surface of 



plates strongly marked with radiating ridges. Basal plates unknown. 



First, second, and third radial plates longer than wide. First interradial 



plate longer than wide ; the succeeding ones about as long as wide. 



Brachial plates as in M. pachydadylus. 

 Arms slender, composed of a double series of slightly interlocking plates, 



with the armlets originating at every seventh, eighth, or ninth plate. 



Tentacula obscure. 

 Column unkno^vn. 



The structure of the body in this species corresponds with the preceding species 

 of this genus; the plates being marked as strongly a.^ m M. ■pachydactylus, while 

 their shape is different, giving the body a more elongate form. 



The specimen is imperfect at the base of the arms, but it appears to be destitute 

 of the auxiliary arms which mark the two preceding species. The arms are more 

 slender, and the armlets are conspicuously more distant than in either of the others. 

 These characters serve to distinguish it from all the associated species yet known. 

 Fig. 5. A specimen preserving the body above the basal plates, and a portion of several of 

 the arms and armlets. 



Geological position and locality. In the shaly layers of the Pentamerus limestone 

 of the Lower Helderberg group, associated with Mariacrinus nohUissimus : Jerusa- 

 lem hill, Litchfield, Heridmer county. 



