104 BULLETIN 64, UNITED STATES NATIONAL MUSEUM. 



Family RHODOCRINID.E Bather. 

 Genus DIABOLOCRINUS Waehsmuth and Springer. 



DIABOLOCRINUS VESPERALIS (White). 

 Gilbertsocrinites americanus Troost, Proc. Amer. Ass. Adv. Sci., II (read 1849), 



1850, p. 61 (nomen nudum). 

 Bhodocrinus vesperalis White, Proc. U. S. Nat. Mus., II, 1879, p. 252, pi. i, figs. 



11, 12. — Wachsmuth and Springer, Rev. Palseocrinoidea II, 1881, p. 212 



(catalogue name). — White, 12th Ann. Rep. U. S. Geol. Surv. Terr., Ilayden, 



1883, p. 129, pi. xxxv, figs. 4a, b. — Miller, North Amer. Geol. and Pal., 



1889, p. 278. 

 Lyriocrinus sculptilis Miller (not Hall, 1851), Journ. Cincinnati Soc. Nat. Hist., 



V, No. 2, 1882, p. 83, pi. in, figs. 6, Ga-b. 

 Lyriocrinus sculptus Miller, Journ. Cincinnati Soc. Nat. Hist., - V, No. 3, p. 117. 

 Archseocrinus sculptus Wachsmuth and Springer, Rev. Palseocrinoidea, III, 



1885, p. 98.— Miller, North Amer. Geol. and Pal., 1889, p. 225 (catalogue 



name). 

 Diabolocrinus vesperalis Wachsmuth and Springer, North Amer. Crinoidea 



Camerata, 1897, p. 251, pi. xi, figs, lc, d. 



The following description is by Troost: 



I believe this species is the first of the genus Gilbertsocrinites established by Phillips, 

 that has been found in the United States. It resembles, in its general form, none of 

 those that are figured by Phillips. (Phillips, Geol. of Yorkshire, pi. 4.) 



It is compressed— globular. The pelvis [infrabasals] which is sunk in an excavation, 

 is small, pentagonal and perforated by a circular, more or less lobated aperture, and 

 divided into five parts. It supports five elongated hexagonal costals [basals] forming 

 a decagon with five reentering angles, which supports five heptagonal 2nd costals 

 [radials] and five pentagonal intercostals [interbrachials], placed in the reentering 

 angles. The heptagonal plates bearing five pentagonal scapulars [primibrachs] 

 from which proceed the arms divided into hands. The capital integument is more or 

 less globular and terminates in the centre in a proboscis-like aperture, and is covered 

 with numerous small polygonal plates. 



It occurs in the vicinity of Knoxville, East Tennessee, which I consider as the in- 

 ferior Silurian, and is associated with Calymene fischerii. 



Observations. — Doctor Troost's specimens are typical and we'll 

 preserved individuals of the species. 



Formation and locality. — Trenton group. Near Knoxville, Ten- 

 nessee. 



Cat, No. 39970, U.S.N.M. 



Genus SIDEROCRINUS Troost. 

 Siderocrinites Troost, MSS., 1850. 

 The specimen upon which this genus is founded shows only the 

 inner surface of the basal portion of a large crinoid which had a 

 deep basal excavation. It retains only the infrabasals, basals, and 

 two radials. The basal excavation of the specimen makes its inner 

 surface convex, and it was naturally mistaken by Troost for the 

 outer surface of a convex form. Farther clearing away of the 

 matrix reveals the presence of a long spine on the outer surface of 

 the radials which determines the orientation of the specimen. Being 

 founded upon a misconception of the nature of the specimen, Doctor 

 Troost's description is misleading and has been omitted. 



