74 



BULLETIN 64, UNITED STATES NATIONAL MUSEUM. 



DIZYGOCRINUS UNIONENSIS DIVALIS (Miller). 



Plate 5, fig. 16. 



Actinocrinites mortonii (in part) Troost, Proc. Amer. Ass. Adv. Sci., II (read 



1849), 1850, p. 60 (nomen nudum); MSS., 1850. 

 Batocrinus divalis Miller, 18th Rep. Indiana, Dep. Geol. and Nat. Res. (Adv. 



sheets, 1892, p. 22, pi. m, figs. 6, 7), 1894, p. 276, pi. in, figs. 6, 7. 

 Dizygocrinus unionensis var. divalis Wachsmuth and Springer, North Amer. 



Crinoidea Camerata, 1897, p. 425, pi. xxxv, figs. 21, 22, 23, 24.— Weller, 



Bull. No. 153, U. S. Geol. Surv., 1898, p. 235 (catalogue name). 



The following description is by Troost: 



A shallow dish shaped cup, composed of small, broad, tumous plates, arranged as in 

 the genus Actinocrinites, but in the A. mortonii, the cup continues for four plates 

 beyond the arm joints, and the division of hands and fingers takes place before the 

 rim or superior margin of the cup is completed. 



In general the cup of the Actinocrinites terminates with the series of the plates 

 formed by the arms, as is mentioned by Miller « (page 99). "We have thus the figure 

 of a cup completely formed, of which the arm joints adhering to the scapula, and 

 several multangular pieces (called by me pectoral plates) belonging to the plated 

 integument form the rim."— In this respect the A. mortonii differs from the genus 

 Actinocrinites; — all the divisions of arms till it arrives at 30 tentaculated fingers, take 

 place on the cup, and the last division which gives rise to the 30 [thirty-six] fingers, 

 forms the superior edge or rim of the cup. Then no ulterior division takes place, so 

 that the whole superstructure of the crinoid is formed of 30 feathered or tentaculated 

 fingers. 



I found only fragments of it in the State of Tennessee. It seems to be more abun- 

 dant in the north of Alabama. I possess a perfect specimen found in the Carbonifer- 

 ous strata in the vicinity of Hunts ville. 



I have dedicated this species to my friend Dr. S. G. Morton of Philadelphia, author 

 of the Crania Americana and of several geological memoirs. 



Observations. — S. A. Miller [1892] described this form as a distinct 

 species, but its relationship with Dizygocrinus unionensis is so close 

 that it is evidently not more than a variety of that species as stated 

 by Wachsmuth and Springer [1897]. 



Formation and locality. — Warsaw limestone. Boon ville, Missouri; 

 Huntsville, Alabama. 



Cat. No. 39902, U.S.N.M. 



Genus LOBOCRINUS Wachsmuth and Springer. 



Lobocrinus Wachsmuth and Springer, North Amer. Crinoidea Camerata, 1897, 

 p. 434. 



Observations. — Two of the species now included in this genus were 

 for a time separated from Actinocrinus under the name of TJperocrinus 

 as a subgenus of Batocrinus. Uperocrinus was first proposed by 

 Meek and Worthen [1865] for forms " having the body below the arms 

 very narrow, and drawn out so as to form a kind of handle to the 

 upper part." In the group were included Actinocrinus pyriformis 

 Shumard, A. pistillus Meek and Worthen, and A. pistilliformis Meek 

 and Worthen. Later, in the Geological Survey of Illinois, V, pp. 



a Miller, J. S. A Natural History of the Crinoidea, 1821.— E. W. 



