DESCRIPTIONS OF THE SPECIES. 239 



occupying quite half the length of the calyx, in others quite small and confined to the 

 vicinity of the summit; the anal deltoid frequently different in shape and appearance 

 from the others. Ambulacra narrow or sublinear, and nearly parallel-sided, some- 

 times deeply impressed within the sinuses, always more or less so at their proximal 

 ends ; lancet-plates narrow and not filling the sinuses, more or less exposed throughout 

 two thirds of the ambulacra ; side plates transversely elongated, but of variable form, 

 from twenty to eighty in number. Outer side plates generally well developed. 

 Hydrospires pendent, usually but a few folds on each side of an ambulacrum, the 

 inner one forming a well-defined hydrospire-plate. Spiracles five, piercing the mor< 

 or less constricted apices of the deltoid plates as round or oval openings, sometimes 

 rising into short erect tubes, and frequently guarded at their outer margins by nodular 

 thickenings. Posterior spiracle including the anus, and forming a large pyriform 

 opening. Mouth usually small, and covered with minute summit-plates, which 

 rarely exhibit any definite arrangement. Column round. Ornament lineate granular. 



History. The origin of the name Granatocrinus may be traced back to the year 

 1840, when Troost designated a new species by the name of Granatocrinites 

 cidariformis, but unfortunately neither genus nor species was ever described. We 

 believe that Prof. James Hall was the first to formally use the name Granatocrinus. 

 in 1862, but without any precise definition, although his observations may be said to 

 have laid the foundation of our knowledge of the genus as it is now understood. It 

 corresponds to a portion of Cumberland's earlier genus Mitra, published in 1826, a 

 name, however, which we are unable to use, from its preoccupation by Lamarck for 

 a genus of Mollusca. We have also little doubt that it was for the British represen- 

 tatives of Granatocrinus that Dr. J. E. Gray proposed the name Orbitrcm ites as early 

 as 1840, so far as we can judge from the list of species appended to this name by the 

 Messrs. Austin in 1S42, in their " Proposed Arrangement of the Crinoidea" 1 . 



Dr. Troost was not the only writer who appears to have seen the necessity for a 

 generic separation of certain forms from the original type of Pentremites, for Drs. 

 Owen and Shumard, commenting in 1852 on their Pentremites Xorwoodi and P. melo 

 (species afterwards placed in Granatocrinus), suggested that they would form the type 

 of a new genus. 



After Hall, Dr. F. B. Shumard appears to have possessed the clearest views on 

 Granatocrinus ; for in 1865 he wrote, '-The Granatocrinus (Pentremites) granulatus, 

 Roemer,= 67. cidariformis, Troost, may be regarded as the type of the genus, and for 

 the present it may be extended 2 , so as to include such species as Pentremites melo, and 

 P. Norwoodi, and allied forms, though it may become necessary after a while to 



1 Ann. & Mag. Nat. Hist. L842, vol. x. p. 111. We may remark for the information of our American 

 fellow-workers, and of Mr. Hambach in particular, that Gray's name has nine years' priority over Troost's, 

 but, like it, is only an MS. name. We feel bound, therefore, to adopt Granatocrinus, though we think that 

 it should be credited to Trof. James Hall rather than to Dr. Troost. - The italics are ours. 



