SAGENOCRINIDAE 217, 



Meristocrinus orbignyi (M'Coy) 

 Plate XVII, fig. 7 



Taxocrinus Orbignii M'Coy, Ann. and Mag. Nat. Hist. (2), VI, 1850, p. 289; (in Sedgwick & M'Coy) 

 British Palaeozoic Fossils, 1854, p. 53, pi. iD, fig. I. — Phillips Murchison, Siluria (3d Ed.), 1859, 

 pp. xx, 246, 536. — Wachsmuth and Springer, Revision Palaeocrinoidea, pt. 1, 1879, p. 49. 



Meristocrinus orbignii, Springer, Jour. Geology, XIV, 1906, pp. 492, 519. 



The species is not well enough known for detailed description, but in con- 

 nection with the next following species it shows the existence of a form of this 

 generic type in the British rocks at two distinct horizons and localities. The 

 only available specimen is the type which is a natural mould of the anterior side 

 only, from which I have obtained a wax impression but not in time for figuring 

 in this work. I reproduce M'Coy's figure which is much restored, but shows 

 the essential characters as they appear in the original, viz., three primibrachs, 

 five secundibrachs, and a large stem with remarkably uniform columnals, not 

 enlarging at the calyx ; it differs in the latter respect from the other species in 

 which the stem is known. 



Type. In the Sedgwick Museum at Cambridge, England. 



Horizon and locality. Silurian, Upper Ludlow formation ; High Thorns, Underbarrow, 

 Kendal, County Westmoreland, England. 



Meristocrinus minor n. sp. 



Plate XVII, figs. 8, p 



A small species. Crown elongate, total height to width at I Ax, 2.5 to 1 ; 

 spread of calyx from base about 1 to 2 ; average specimen, 10 mm. high by 4 mm. 

 wide ; base, 2 mm. 



IBB low, like a short columnal. BB small. RR twice as large as BB, or as 

 the succeeding IBr. IBr 3. IIBr 5. Anal and iBr areas distinct, the latter 

 apparently without solid plates and filled with perisome. Column large, with 

 conical expansion proximally, in which the columnals are very thin, becoming 

 thicker and uniform below. 



I have proposed this species upon the evidence of three specimens which show great uni- 

 formity in size and other ascertainable characters. The posterior side is visible only in one 

 (PL XVII, fig. 9), and there the anal plates are indistinct, being pushed inward; apparently 

 the first anal plate is firmly wedged in between the large radials, and is followed by a vertical 

 series leaning toward the right posterior ray. The latter ray plainly shows the five plates in 

 succession, viz., RA + R + 3 IBr. The two specimens were obtained by me at Dudley in 1887, 

 and referred to M. orbignyi. The subsequent discovery of a third specimen from the same 

 horizon and locality, identical with them in size and stem characters, indicated a persistence 

 of type which cannot well be ignored. They occur in the shales at the base of the Wenlock 

 beds, a horizon considerably lower than that of M. orbignyi, which also comes from a differ- 

 ent and somewhat distant locality. The expanding stem of the present species is sufficient to 

 distinguish it from the last, and the very small infrabasals from the Swedish species. 



Types. That of figure 9 is in the author's collection ; of figure 8 in the British Museum. 



Horizon and locality. Silurian, Wenlock shales ; Dudley, England. 



