TROOST *S CRINOIDS OF TENNESSEE E. WOOD. 



107 



Class ECHINOIDEA Agassiz. 



Order MELONITOIDA Gregory. 

 Genus MELONITES Norwood and Owen. 



MELONITES MULTIPORA Norwood and Owen. 



Doctor Troost records the occurrence of Melonites multipora in 

 Tennessee. He says of these specimens: 



The plates of the Melonites which we find in Tennessee and which coincide with 

 the figures of the assulae Asteria quinquelobe of Goldfuss (see loco, cit.) are short 

 hexagonal prisms more or less laterally compressed, wedge shaped, superior or exter- 

 nal surface, generally smooth. 



The animals to which these plates belonged must have been very abundant at 

 the period of the formation of our lower Carboniferous or Superior Devonian Strata 

 which prevail in Stewart, Montgomery, Humphreys and Dickson Counties namely 

 over the principal iron region of Tennessee — some parts of the strata are almost en- 

 tirely made up of these plates — and large numbers of them may be collected from 

 the disintegrations of these rocks — they are siliceous and generally associated with 

 Cidarites tennesseese, Pentremites Jtorialis, Trilobites (Calymene?) joints and other 

 parts of crinoids, (circular and elliptical") Fenestellae and fragments of shells- 

 bivalves). 



MELONITES GRANULATUS Troost. 



Melonites granulatus Troost, MSS., 1850. 



Compare Melonites giganteus Jackson, Bull. Geol. Soc. Amer., VII, 1896, p. 

 172, pi. iv, fig. 19; pi. v, figs. 21-24. 



The description by Troost is as follows : 



The fragment of this fossil which is in my possession is small and is composed of 

 parallel ridges or undulations, three elevations and two depressions, and it is so 

 indefinite that I cannot vouch that it really belongs to the Melonites. Nevertheless 

 the form and the arrangement of the plates show a great analogy to this genus. If 

 so it must form a distinct species of it. 



It is composed, 1st., of a longitudinal elevation of about 3 cent. met. broad, of 

 granulated, hexagonal plates of different sizes interlocking each other (the fragment 

 contains six rows but it is only part of the elevation). 2nd. Then follows a depressed 

 field running parallel to the elevation, of about 12 mil. met. transverse, on which 

 follows, 3rd., an elevation which is about 10 mil. met. transverse, and this is suc- 

 ceeded, 4th, by a depression like the 2nd., and 5th., an elevation like the 3rd. My 

 fragment goes no farther. 



The first large longitudinal elevation, as stated above, is constructed of hexagonal 

 plates. The second, the depressed field, — on this no joints of hexagonal plates are 

 perceptible, but it exhibits several pairs of pores placed in a regular order. 



The third elevation is again composed of hexagonal plates like the principal one 

 [but less regular in shape and smaller], the fourth is again constructed like the above 

 described bi-porous field, while the last elevation is constructed of hexagonal plates. 

 The fragment in my cabinet which seems only a small part of a whole, is three inches 

 transversely, and the surface of the plates from 5 to 7 mil. met. transversely, so it 

 seems it was much larger than the M. multipora the whole of which measured trans- 

 versely, according to Norwood and Owen, 4.2 inches. 



It occurs in East Tennessee between Tazewell and Cumberland Gap, Claiborne 

 County. It is carbonate of lime and imbedded in limestone which resembles the 

 compact Silurian limestone of the vicinity of Nashville. In this respect it differs 

 from the preceding species which is siliceous and occurs in a higher geological posi- 

 tion. The geological disposition of the place where I found it is difficult to deter- 



