204 DEVONIAN FAUNA. 



3. Genus. — Rhodocrinus, Miller, 1821. 

 1. Rhodocrinus (Acanthocrinus), sp. Plate XXIV, figs. 6, 6 a. 



Remarks. — A small decorticated specimen from Wolborough in the Museum of 

 Practical Geology deserves notice. It is a basal or radial plate in the form of a 

 regular hexagon, which is produced centrally into a very elongate, conical, gently 

 arching spine. The margins of the plate slope inwards and are slightly grooved 

 laterally. It measures 4 mm. across and 11 mm. in length. 



It seems exactly to correspond with the spiniferous basal and radial plates of 

 Acanthocrinus longispinus, F. A. Romer, 1 as figured and described by Miiller ; 2 the 

 only difference being that in the latter the spines appear straight instead of 

 arching. 



An almost identical (but straight) specimen was described as a calyx under 

 the name of Eugeniacrinus ? hexagonus by Minister 3 from the Carboniferous of 

 Tournay, and doubtless belongs to a kindred species. 



Wachsmuth and Springer 4 consider that Acanthocrinus cannot be distinguished 

 from Rhodocrinus even as a sub-genus. 



2. Order.— INADUNATA, Wachsmuth and Springer, 1886. 



1. Sub-order. — Larviformes, Wachsmuth and Springer, 1886. 5 



I. Family. — Haplocrinid,e, F. Romer, 1855. 



1. Genus. — Haplocrinds, Steininger, 1834. 



Calyx small, subglobose. Basals five, small, pentagonal. Radials five; left 

 posterior and anterior consisting of single heptagonal plates, and the other three 

 horizontally bisected ; all with the upper articular faces horizontal. Tegmen 

 consisting of five triangular orals, laterally grooved to receive the arms. Anal- 

 opening under the upper angle of the posterior oral. 



Devonian and Carboniferous. 



1 1850, F. A. Eotner, ' Neues Jahrb. f. Min.,' p. 079, pi. vi, fig. 1, 2 



-' L855, Miiller, in ' Zeiler und Wirtgen, Verb. N. Vereins,' vol. xii, p. 8, pi. ii, figs. 1 — 3, and 

 pi. iii, figs. 1, 2. 



3 1839, Miinster, ' Beitr.,' pt. i. p. M, pi. i, fig. 6. 



1 1881, Wachsmuth and Springer, ' Proc. Acad. N. S. Philad.,' p. 354. 

 In place of Larviformes and Fistulata, Mr. Bather (in 1S93, ' Crinoidea of Gotland,' pt. 1, 

 p. 20) tentatively divides the Tnadunata into Monocyclica and Dicyclica, regarding the existence of an 

 infra-basal circlet as being in this order of sufficient importance for a primary division. 



