ICHTHYOCRINIDAE 333 



Wachsmuthicrinus iowensis n. sp. 



Plate XLIV, fig. 8 



Similar to W. thiemei, but with rays and their divisions strongly divergent, 

 and numerous interbrachials, beginning with a very large one resting on the 

 shoulders of the radials. The rays are angular below, with small nodes on the 

 lower brachials, and rounded without nodes above. Ramules about every third 

 brachial. There is but a single specimen, considerably flattened in a vertical 

 direction by pressure, which may increase the apparent divergence of the rays. 



I have hesitated to propose a new species upon this single and somewhat unsatisfactory 

 specimen, and if it belonged to the same horizon as those of W. theimei I should regard it 

 as merely a further extension of the variations of that species. But it occurs in the Upper 

 Burlington beds, associated with Dorycrinus missouriensis and other characteristic fossils ; 

 and very few species are known to pass unchanged from the Lower beds to this horizon. 

 This fact would indicate that the increase in size and number of interbrachial plates, and con- 

 sequent greater spreading of the crown, had probably become a fixed character. I should 

 •expect that other specimens, if ever found, would confirm the separation. This is the latest 

 occurrence of the genus, and it must have been almost extinct, as no other specimen has ever 

 been found from the Upper beds in all the collections made at Burlington during half a 

 century. 



Type. Author's collection. 



Horizon and locality. Lower Carboniferous, Upper Burlington limestone; Burlington, 

 Iowa. 



Wachsmuthicrinus ponderosus n. sp. 



Plate XLIV, figs, pa-c 



A large species. Crown elongate, with rays in close contact above iBr. 

 Interbrachials well developed as high as the third axil. Rays and their divisions 

 rounded ; the outer one largest. Ramules very large, branching again, approach- 

 ing the main ramus in size at about the third bifurcation, and probably extend- 

 ing to its full length. Sutures sinuous, surface of rays finely pustulose. Crown, 

 45 mm. high, and about 38 mm. wide at the second bifurcation. 



The imperfect condition of the specimen precludes a more detailed description. The 

 entire calyx is exfoliated below the IIBr, and the suture lines are traced with some difficulty 

 on the surface of the internal cast. So far as can be ascertained the crown is perfectly sym- 

 metrical, with a series of three or four interbrachial plates in the primary axil, and others in 

 the second and third, and without any differentiation of the anal side. The base cannot be 

 made out. If this interpretation is correct the form must fall within this genus as a variant 

 in the matter of large ramules, somewhat like D. tardus in Dactylocrinus; it is of special 

 interest as the first indication of the genus outside of America. 



Type. British Museum, No. 75696. 



Horizon and locality. Lower Carboniferous ; Jedburgh, Scotland. 



