37 



ages. The vault is covered with small polygonal plates. The 

 azygous opening is not preserved in our specimen. The words 

 "pseudo-ambulacral appendages" are quite errDueous, when applied 

 to this species or to the genus to which it properly belongs. If 

 we now turn our attention to the vault, which is well shown in 

 the illustration, we see the ambulacral areas, the ambulacral 

 openings, and the plates in the intersecondary areas connecting 

 with the vault, as the same parts may be seen in other genera. 

 The depressions in the interradial areas are the same. In other 

 genera we have two orifices and sometimes four, six, or eight 

 penetrating the vault between the arms, which have been sup- 

 posed by some to be ovarian apertures, and this view is supported 

 by the established fact from numerous observations, that they are 

 escurrent orifices. They are the same in the species under con- 

 sideration, the difiPerence being, that in this species, small plates 

 covering these "ovarian apertures" are continued so as to cut off 

 the interradial depressions, and present the ends of the canals 

 upon the outer edge or beyond the outer edge of the plates of the 

 calyx, while in other genera and species the "ovarian apertures" 

 are confined to the plates of the vault, and open gutters lead 

 from them across the plates to the outer margin of the plates of 

 the calyx. The structure of these orifices we have fully defined 

 in vaiious species of Dolaiocriniis and Baiocrinus, and very 

 clearly they are not "pseudo-ambulacral appendages" in those gen- 

 era, and for the same reason, we think, they are not in the spe- 

 cies before us. 



This species is congeneric with the species first described by 

 Hall as Tremafocrinus spinigerus and subsequently referred by 

 him to Gilberlsocrinus, and later referred to Gilberlsocrinus by 

 Whitfield. It is not a Goniasteroidocrinus, and if belonging to 

 any defined genus, it is to Gilbertsocrmus. We have no speci- 

 mens belonging to the type of Gilberisocrinus for comparison, 

 and the definitions and illustrations by English authors are very 

 obscure and unsatisfactory. It is very plain, however, that Gil- 

 berisocrinus and Goniasieroidocritiiis are distinct genera, and 

 that our species is nearer Gilbertsocrinus than Goninsteroidocri- 

 nus. It is quite probable that Gilbertsocrinus is confined to the 

 Bubcarbouiferous rocks of Europe, and is not an American genus, 

 and that Gilbcrisocritnis spinigerus and the two species described 

 in this Bulletin belong to an undefined Devonian genus. We are 



