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Cincinnati Society of Natural History. 



sharp ridges upon each side of the angular depressions. There are 

 only a few of these ossicles preserved on our specimen, and they may 

 be described as rather small club-shaped pieces. They are not half as 

 large as those belonging to P. dyeri. 



This magnificent species can hardly be mistaken for any other, as it 

 is very distinct in all its characters. The specimen is from the collec- 

 tion of I. H. Harris, of Waynesville, and was collected in the upper 

 part of the Hudson River Group of that locality. 



Heterocrinus constrictus (Hall). 



(Plate IV., Fig. 4, fragment, natural size; Fig. 4<z, opposite side of the same specimen, 

 showing the peculiar change that has taken place, that led to the mistake of calling it by 

 a different specific name; Fig. 45, the upper end of the head of another specimen, showing 

 the armlets or smaller arms.) 



Fig. 4 represents this species as it is usually found. Fig. 4a is the 

 opposite side of the same specimen, and shows the characters that 

 misled Prof. Wetherb}^ into describing it as a new species under the 

 name of Heterocrinus vaupeli. The metamorphosis or peculiar min- 

 eral change that has taken place is calculated to deceive any one on 

 first inspection, and it is to the credit of Prof. Wetherby that he was 

 able, from his specimen alone, to compare it even with H. constrictus, 

 to which it belonged. This peculiar change may have taken place 

 during life. Several specimens are now known showing it in a greater 

 or less degree, which belong to this species. The specimen repre^ 

 sented by fig. 46 shows the change near the end of the arms on one 

 side, but this character is not shown in the illustration. If the change 

 is to be attributed to fossilization, it is unaocoun table that we should 

 be unable to find the same change in other crinoids found in the same 

 rocks; but if it occurred during life, it may have been the result of dis- 

 ease that afflicted this species. I have not recognized the peculiarity 

 in other species, but other collectors claim to have seen it in other 

 species belonging to this genus. 



Prof. Meek seems to have been in doubt as to whether the smaller 

 branches of the arms in this species should be called pinnules or arm- 

 lets. Fig. 46 is drawn for the purpose of showing better than has 

 heretofore been done, the characters of these smaller branches. They 

 are furrowed, and the furrows are connected with the larger ambu- 

 lacral grooves. The}' are not, therefore, pinnules. They may be called 

 armlets, but they are the result of unequal bifurcations of the arms, 

 and are none the less arms because they are smaller than the larger 

 division or main arm. These smaller arms bifurcate at least once, and 

 toward the upper part of the arms they bifurcate twice. These divis- 



