200 CATALOGUE OF THE BLASTOIDEA. 



limbs, just as in Roomer's first figure of Pentremites Reinwdrdti. But, like the four 

 normal deltoids of that species and those of Pentremitidca, Cryptoschis'ma, Codaster, 

 P/iamoschisma, Triccelocrinus, and, we may also add, of Stephanocrinus (PI. V. figs. 1, 

 3, 17, 24 ; PI. XL figs. 5, 6 ; PL XII. figs. 2, 5, 6 ; PL XIX. figs. 12, 13), they are over- 

 lapped externally by the radial limbs. This is well shown in our figure of Troosto- 

 crinus Reinwardti on p. 193 ; and it is very evident in some of Mr. Wachsmuth's 

 smaller specimens. The position of the radio-deltoid sutures upon the high walls of 

 the radial sinuses is almost a vertical one, i. e. parallel to the long axis of the calyx ; 

 and they consequently meet the ambulacra at rather a sharp angle and not almost 

 transversely, as in Triccelocrinus (PL XIX. figs. 13, 15), or in Codaster and Crypto- 

 schisma (PI. V. fig. 24 ; PL XII. figs. 1-6). Phcenoschisma acutum resembles Codaster 

 (PL XIV. figs 11, 12); but P. vobile and P. Vemeuili are more like Metablastus 

 lineatus in the position of the radio-deltoid sutures (PL XL figs. 1-3, 5, 0). 



Although cut off from the exterior of the calyx by the overlap of the radial limbs, 

 the deltoids of this species are very conspicuous objects in the summit ; for they form 

 high ridges between the linear spiracles (PL III. fig. 14), which almost reach the 

 edge of the extremely contracted peristome, and are very plainly visible in an inter- 

 radial view of the calyx. They are of greater relative height in this species than in 

 any other form of Metablastus that we have seen. It seems to be not unlike 

 M. IVortheni, Hall, sp., as was suggested by Shumard; but, as far as we can make out 

 from Hall's figure and from the two crushed specimens of his type which we have 

 seen, the Keokuk species has relatively longer ambulacra and a considerably stouter 

 basal cup than M. lineatus. We know too little of the other Keokuk species 

 described by Hall (M. bipyramidalis) to be able to compare it with the Burlington 

 form ; but the latter differs considerably from the two specimens of Metablastus 

 which occur in the Warsaw Limestone, viz. M. Yarsouviensis, Meek and Woithen, 

 sp., and M. Wachsmuthi, Gurley, sp. We think that we have identified both of 

 them in Mr. Wachsmuth's collection, and in each case the base is shorter, less tapering, 

 and much more distinctly trihedral than in M. lineatus. In fact, they are the con- 

 necting links between this genus and Triccelocrinus, but they do not present the three 

 hollows on the interbasal sutures which form the essential characteristic of this 

 genus (PL XVI. figs. 17, 18; PL XIX. figs. 13, 14). 



Locality and Horizon. Burlington, Iowa: Upper Burlington Limestone, Subcar- 

 boniferous. 



Metablastus Hispanicus, K. & C. 



(PL V. fi-. 21.) 

 Troostocrinus Hispanicus, E. & C, Ann. & Mag. Nat. Hist. 1883, vol. xi. p. 845. 

 Sp. Char. Calyx elongated, robustly subfusiform ; summit rounded, but the 

 characters not well preserved ; basal cup conical, its sides being compressed and 

 flattened below, so as to give it a triangular form ; section pentagonal, with concave 



