78 DAVENPORT ACADEMY OF NATURAL SCIENCES. 



" hyii/'ospire-pores." The sui)plementary pore-pieces of Roemer are 

 the "outer side-plates.'' Beneath the ambulacral fields are the '^ inter- 

 radial systems of lamellar tubes or hydrospires." The openings of these 

 tubes, if directly on the ventral surface of the calyx as in Codaster, are 

 called the "hydrospire-slits;" if they are concentrated beneath the am- 

 bulacra as in Orophocrinus^^ the gap between the edge of the lancet- 

 plate and the sides of the radial sinus is the '' hydrospire cleft.'" This 

 leads downward into the " hydrospire cafial." The canals oi)en exter- 

 nally by the "spiracles" formerly called ovarian openings. The spira- 

 cle or spiracles of the anal interradius may be confluent with the anal 

 opening to form the "anal spiracle." The plates covering the mouth 

 and peristome, and which are sometimes continued down the ambu- 

 lacra covering the food grooves, are the " summit plates or the I'ault." 



They further use the term "oro-anal side" for the upper truncate 

 regions of the body, and they include herein the ambulacra. 



It has been asserted by Mr. Lyon (Owen's Kentucky Rep., Vol. 

 III., p. 468), that in the genera Codaster and Pentremites the plates 

 generally known as basals consisted of two successive series of pieces, 

 and upon this ground he proposed a new formula for the two genera. 

 Only to the "lower series" of plates he applied the term basals; the 

 "upper series" he called first radials. He explains the deficiency from 

 five to three in the number of the latter plates, and the irregularity 

 which he found in their form and position, compared with other radials, 

 that the two equal hexagonal pieces were perfect plates, and the third 

 smaller pentagonal one, imperfect. According to his theory, there 

 were no first radials in two of the rays, an(^ the rays commenced with 

 a second radial; This curious interpretation of the plates, as might be 

 expected, found no followers, but his view that in some of the lUastoids 

 the plates formerly called basals were composed of two series of three 

 pieces each, was afterwards accepted by Billings (Amer. Journ. Sci. 

 and Arts, July, 1869), and also by Meek and Worthen (Geol. Rep. 111., 

 Vol. v., p. 464). The former regarded the "lower pieces" as basals, 

 the "upper ones" as subradials; while Meek and Worthen, in rede- 

 scribing Orophocrinus ( Codonites ) stelliformis., O. and Shum., distin- 

 guished the two series as basals and supplementary basals, the latter to 

 be applied to the "lower series." They objected to the name subra- 

 dials from the fact that the plates do not alternate with each other. 



*Meek and Worthen, in defining, in 1S69 (Geol. Rep. 111., Vol. V., p. 464), the genus Codon- 

 ites, were evidently not aware that Von Seebuch had proposed, in 1S64 (Nuchr. K. Geselloch. zu 

 Goettingcn, p. no), for Pentremites stelliformis Owen and Shum. the genus Orophocrinus. The 

 latter has since been adopted by lAidwig, Zittel, and by Etheridge and Carpenter. 



