HEXACRINUS. 193 



conical. Probably it had no interscapular plate." Both the above specimens 

 are very poor and worn, but they evidently belong to the same species ; and other 

 better specimens can be identified with them, which show, among other things, 

 that an " interscapular " or anal plate did exist in the species. They evidently 

 do not belong to the species referred to PL tuberculatus by Phillips 1 in the 

 ' Geology of Yorkshire,' nor, I think, to the true PI. tuberculatus, Miller. 2 The latter 

 appears to be a Carboniferous form, and is very imperfectly described, but seems 

 to differ among other things in its style of ornamentation and its pentagonal basal 

 circlet. It is identified by Wachsmuth and Springer 3 with PL ellipticus, Phillips, 4 

 in part, and with PL tuberculatus, Austin, which seems probably to represent it. 

 Consequently Austin's 5 name, H. macrotatus, becomes the name of the species. 



The tegmen is well seen in a remarkably fine specimen in the British Museum. 

 It is very much smaller and lower than the dorsal cup. It has a very large 

 polyhedral central or "posterior oral" plate, surrounded by a circle of nine other 

 large plates. Of these the four anterior are pentagonal, and seem to be the other 

 oral plates ; the posterior is a massive anal in the shape of a wedge or bird's 

 breast, which rests upon the intercalated anal of the radial circlet ; while the 

 circle is completed on each side by two smaller pentagonal plates which may also 

 belong to the anal system. The distal plates are very small in this specimen 

 and too indistinct for description. 



Affinities. — H. granifer, F. Romer 6 (which seems incorrectly identified with 

 H. interscapularis by Schultze), differs from this species by having a shorter cup, 

 shallower suture-lines, less confluent ornament, and larger and more numerous 

 interambulacrals. The anal plates are also unlike, consisting of an intercalated 

 anal surmounted by more than a second single plate. 



Schultze 7 doubtfully identified Phillips's PL tuberculatus with PL fritillus, 

 Miiller, 8 but that species is evidently totally distinct from the present. It 

 differs generically, and the large size of the attachment of its column and the 

 smallness of the radials compared with the basals are points which easily 

 distinguish even imperfect specimens. 



H. anaglypticus, Goldfuss, 9 seems to approach the nearest to it of Eifel 



1 1838, Phillips, ' Geol. Torks.,' vol. ii, p. 201, pi. iii, tig. 17. 



2 1821, Miller, 'Nat. Hist. Cricoids,' p. 81, pi. xxviii, fig. 1. 



3 1881, Wachsmuth and Springer, ' Proc. Acad. Nat. Hist. Philad.,' pt. 2, p. 249. 



4 1838, Phillips, ' Geol. Torks.,' vol. ii, p. 204, pi. iii, fig. 19 (only). 



5 1843, Austin, 'Monogr. Eecent and Foss. Criuoids,' p. 41, pi. iv, figs. 3m— y. 

 G 1852, F. Romer, ' Verhandl. n. Vereins. Rheinl.,' vol. ix, p. 281, pi. ii, fig. 1. 



7 1867, Schultze, ' Densch. k. Acad. Wissen. Wien,' vol. xxvi, p. 181. 



8 1855, Miiller, in Wirtgen and Zeiler, ' Verhandl. a. Vereins Rheinl.,' vol. xii, p. 80, pi. x, figs. 4, 5. 



9 1839, Goldf., 'Nov. Act. Akad. Leop.,' vol. xix, pt. 1, p. 348, pi. xxxii, fig. 4; and 1867, 

 Schultze, 'Denksch. kais. Akad. Wissensch. Wien,' vol. xxvi, p. 184, pi. viii, Kg. 1. 



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