INDIANA PALAEONTOLOGY. I26. 



P E N T R E M I T E S C O N O I 1) E U S . Hall. Rowley. 



Plate 8G. Fk^s. 41. 4-2, 43. 44. 



Figure 41 is a specimen with five radial plates, but only four ambulacra, 

 the fifth radial being somewhat shorter than the rest, narrower and merely 

 creased down the middle, where the ambulacrum should be. There seems to 

 be but one deltoid above this abnormal fork piece and that too, is creased in 

 like manner and has the outline of a double piece. 



The abortive radial is directly opposite the anal opening. 



The summit openings are but four. 



Figure 42 is a ventral view of another so-called four-sided specimen, dif- 

 fering in no wise from the above specimen except that the anal opening is 

 directly above the crease in the double deltoid. 



Figure 43 is a deformed specimen in which two of the ambulacra are little 

 more than iialf the length of the other three. 



Figure 44 is a side view of a much smaller, normal specimen with some 

 stem joints attached to the base. 



The chief character of P. ronnideus are the cone shape of the body, the 

 strongly lobed character of the ambulacral region, the narrowness and convex- 

 ity of the ambulacra themselves, the relatively long deltoids that do not reach 

 the summit. The large, mature specimens usually have a flat base, but smaller 

 examples often have the base quite convex, approaching in this particular. 

 P. kon'tiii^kiinus, which Etheridge and Carpenter make a variety of the former. 



Warsaw limestone. Lanesville, Ind. 



P E N T R E M I T E S K X I N C K A N U S. Hall. Rowlev. 



Plate 36. Fi<v. 45. 



Our figure is of an elegant little specimen, preserving some of the stem 

 joints in place. 



The main differences between this and /*. >;,nnnj< >is is in the propor- 

 tionate length of the ambulacra, which in kon'rn'-k'itiiis are not more than half 

 the length of the body, while in adult' P. con-^tulAUs they are full body length. 

 In narrowness and convexity of the ambulacra the two species agree. In 

 koninckanus the bounding edges of the fork pieces and deltoids are more 

 sharply outlined above the ambulacra. As in rnnu'i<h-vx the body is strongly 

 lobed. The anchylosis of the basal stem joints in these little blastoids explains 

 well the presence of the so-called basal plates of Lyun. There is yet a better 

 illustration of that in (Jrophorr'mus steU'iforiiihs. 



-The specimen illustrated (Fig. 45) is from the Warsaw limestone of Lanes- 

 ville, Ind. 



