284 CATALOGUE OF THE BLASTOIDEA. 



agrees with Codaster, but in other respects differs from that genus, and from other 

 genera of Blastoidea. It may be necessary to create a section or subsection under 

 another name to receive it." This suggestion was in fact carried out in 1869 by 

 Messrs. Meek and Worthen 1 , who proposed the name Codoaites for the same species, 

 on the ground of its differing from Pentremites in " having the so-called ovarian 

 pores represented by ten distinct slit-like openings " (PL XI. fig. 9 ; PL XV. fig. 11). 

 They further confirmed some previous observations of Dr. C. A. White's, made in 

 1863, on the presence of tegminal plates covering the mouth and ambulacral 

 grooves 2 . A more detailed description of Codonites by Messrs. Meek and Worthen 

 appeared in 1873, wherein they pointed out how their genus agreed with, and 

 differed from, Pentremites and Codaster 3 . The views enunciated by Dr. White and 

 by Messrs. Meek and Worthen were criticized and generally supported by the late 

 Mr. Billings, who was led, from the structure of the hydrospire-clefts and the 

 absence of " ambulacral pores," to consider Codonites as a Cystid rather than as 

 a Blastoid 4 . The identity of Codonites with Orophocrinus, which had been univer- 

 sally overlooked, was first noticed by Ludwig 5 in 1878; and von Seebach's genus 

 has been since acknowledged by Zittel 6 , by ourselves 7 , and by Wachsmuth 8 . It is 

 true that the definition of Codonites as given by Meek and Worthen is much more 

 complete than that of Orophocrinus by von Seebach ; but nevertheless the latter is suffi- 

 ciently full to claim priority for its author. The fact, however, that four writers had 

 selected the same type as worthy of generic distinction, shows how very important 

 are the characters of Pentremites stelliformis from a morphological point of view. 



Remarks. Orophocrinus, like all the Codasteridae, differs from the other genera of 

 regular Blastoids in the absence of hydrospire-pores, so that there is but one series 

 of openings leading to the hydrospires, viz. the ten more or less elongated clefts at 

 the sides of the ambulacra. They are really only the unclosed portions of the radial 

 sinuses, and correspond to the open hydrospire-canals of a Pentremites after the 

 removal of the side plates which naturally roof them in (PL XII. fig. 13 ; PL XV. 

 figs. 8, 10). As in Pentremites, there is an under lancet-plate, at any rate in the 

 three typical species of Orophocrinus (PL XV. figs. 4, 10, 13). It only occupies the 

 middle of the sinus in 0. pentangularis, so that a wide cleft remains at its sides 

 through which the hydrospires are visible. But the presence of the other ambu- 

 lacral structures which rest on the under lancet-plate reduces this cleft considerably, 

 as seen in PL XV. fig. 8. It is further reduced in 0. verus (PL XV. fig. 4) and still 

 more so in 0. stelliformis (PL XV. fig. 13), in which type the only communication 



1 Proc. Acad. Nat. Sci. 1'hilad. 1869, p. 84, note. 



2 Boston Journ. Nat. Hist. 1863, vol. vii. no. 4, p. 486. 



8 Report Geol. Survey Illinois, 1873, vol. v. p. 463. ' American Journ. Sci. 1870, vol. 1. p. 234. 



5 Zeiteohr. f. wis*. Zool. 187^, Bd. xxxi. p. 388. ,; Handb. Pal. 1870, lid. i. lief. 3, p. 434. 



' Ann. & Mag. Nat. Hist, 1882, vol. ix. p. 249. I Irport Geol. Survey Illinois, 1883, vol. vii. p. 347. 



