64 Thirty-first Report on the State Museum. 



NOTE UPON THE LEGS OF TRILOBITES. 



Some months since, I received from Mr. S. A. Miller, of Cincinnati, 0., a small 

 slab of stone, from the Hudson River group, at Cincinnati, upon which there is 

 a slender six-jointed leg of some crustacean, and fragments of three other legs. 

 More recently, Dr. C. A. Miller has kindly loaned me a slab, obtained at the 

 same locality, which has the remains of ten legs upon it. The legs are scat- 

 tered among fragments of Trilobites of the genera Asaphus, Calymene, 

 Acidaspts, and Trinucleus, and remains of Brachiopods and Bryozoans. 

 The test forming the joints is thin, and differs from the test of the Trilobite in 

 being crushed without breaking, and in a generally more membraneous appear- 

 ance. Four of the legs have six joints each. Figures 6 and 7, Plate 1, show 

 two of these legs enlarged to two diameters. The joints are somewhat flattened. 

 With the exception of the terminal one, each joint is slightly contracted at its 

 lower end, and then expands, forming the articulation for the succeeding joint. 

 The only crustacean known to have existed at the time of the deposition of the 

 rocks of this group, that could have had such legs, is the Trilobite. Judging 

 from the size of the legs, they must have belonged to an individual of the 

 genus Asaphus or Calymene. To the legs figured by the late Prof. E. 

 Billings {Quart. Journ. Geol. /Soc, Vol. xxvi, pi. xxvi, Nov. 1870, January, 

 1879), in a specimen of Asaphus platycephalus, they have a strong resem- 

 blance. 



A discussion of the views of various authors upon the structure and relations 

 of the Trilobite is reserved for a future article, in which, also, the structure of 

 the mouth and branchiae of the Trilobite will be given more fully than in the 

 preceding article. 



