FOSSILS OF THE BURLINGTON GROUP. 463 



GEistis CODOXITES, M. and W. 



Pentremiteg (sp ), ofOwEX and SHUMARD, and others; (notofSay). 



Codaster (sp.). of SHUMARD;* (not of McCoy). 



Codoniteg, MEEK and WORTHEX, 1869. Proceed. Acail. Xat. Sci., Phila. 



This geuus agrees with Pentremites, excepting in the following im- 

 portant characters : in the first place, its opening corresponding to that 

 usually considered the vent, in Pentremites, is proportionally larger, 

 more remote from the center of radiation, and entirely distinct or 

 isolated from the aperture on each side of it, corresponding to a part 

 of those generally called ovarian pores, in the Pentremites (Hydrospires 

 of Mr. Billings). These latter openings in the type under considera- 

 tion also differ from those of Pentremites in appearing at the surface 

 as teu .separate, elongated slits, situated one on each side of the so- 

 called pseudo-ambulacra! areast, instead of forming, with the anal open- 

 ing, five round apertures. The typical species (Pentremites stelliformis, 

 O\ven and Shumard,) also shows twelve of the elongated folds or com- 

 pressed tubes of thin calcareous matter under each of the pseudo-ambu- 

 lacral areas, instead of about eight, as in all the true Pentremites, so far 

 as we have examined. This, however, may not be a generic difference, 

 taken alone. We likewise believe the typical species to be entirely des- 

 titute of any of the pores seen penetrating the pseudo-ambulacra in the 

 true Pentremites, which, according to Mr. BiLLiNGr's observations, is the 

 case with Codaster. 



Compared with Codaster, our genus is found to differ in having only 

 two of the slits mentioned in each iuterradial area, instead of from 

 about eight to sixteen, and in having these openings equally developed 

 in the anal as well as the interradial areas. Its internal calcareous 

 compressed tubes are also placed under the so-called pseudo-ambulac- 

 ral areas, as in the Pentremites, instead of occupying the whole inter- 

 radial areas, as in Codaster. It therefore seems to be an intermediate 

 type between Codaster and Pentremites, but more nearly allied to the 

 latter than to the former. 



As in Pentremites, the typical species shows, in adult examples, three 

 firmly anchylosed pieces, forming, together, a protuberance under the 



" It is due to our lamented Mend, Dr. SHI'MAKD. that we should explain here, that in placing the 

 type of this genus provisionally nnder Coda-tier, he remarked that it differs in several important char- 

 acters from that group, as well as from Pentremites, and that he thought it probably belongs to a dis 

 tinct group from tlu-in both. 



f We regard the so-called pore pieces in the Blastoids as merely recumbent arm pieces similar to 

 those of many Cystoidea, hence we think it would be more proper to call the pseudo-ambulacral areas, 

 bracliial furrows, though for the present we use the term pseudo atnhulaeral areas, in the sense now 



in nf-nrnil iisi-. 



