230 CATALOGUE OF THE BLASTOLDEA. 



to place under Elwacrinus, belong, however, to an altogether different type of Blas- 

 toid structure. A few years later, however, he adopted Hall's suggestion 1 ; but the 

 genus Granatocrinus was never properly defined till 1866, when some valuable 

 remarks upon it were published by Messrs. Meek and Worthen 2 . They included in 

 it, not only P. Sayi, which is the type of our Schizoblastus, but also P. Nbrwoodi and 

 P. melo ; and they described the spiracles of these two types as " piercing directly 

 through them (deltoid plates), so that each pair appears externally as a single opening, 

 though they divide into two distinct canals before passing entirely through the plates." 

 This is indeed true of P. Norwood!, as seen in our PI. VII. figs. 5-8, but it is not 

 the case in P. melo (figs. 14, 15) ; and it was perhaps the knowledge of this fact which 

 led Meek and Worthen to remark in a footnote : — " In worn or weathered specimens 

 of G. melo and G. Norwoodi these little interradial pieces have been so much eroded 

 as to expose each pair of these openings entirely distinct, when they were really 

 united, and appeared as a single opening externally, before wearing." It is quite true 

 that a double spiracular opening is occasionally visible in G. JYorwoodi (PI. VII. 

 fig. 12), but it is the normal condition of G. melo (figs. 14, 15). In fact, Meek and 

 Worthen had already recognized this condition in 1861 3 , before Hall's reference of 

 P. melo to Granatocrinus. Speaking of P. melo and of its ally P. project us, t\\ey 

 sa ic] : — " Both these forms differ from the typical species of the genus Pentremites in 

 having each pair of ovarian openings distinctly separated, instead of closely united, 

 with merely a thin septum between. In this character, as well as in form and the 

 prolongation of the pseudo-ambulacral areas, they agree with the genus Nuclcocrinus 

 of Conrad (=Eleacrinus, Roemer), from which they differ in having the anal and 

 oral openings distinct, as in the true Pentremites. They constitute a subgenus of 

 Pentremites, occupying a position between the typical forms of that genus and 

 Nuclcocrinus." 



In these valuable remarks we entirely concur 4 , and we much regret that the 

 authors did not take any further steps to establish a new subgeneric type on the cha- 

 racters which they so clearly specified. They would thus have anticipated Hall's 

 transfer of P. melo and P. Norwoodi to Granatocrinus, a step in which they after- 

 wards concurred ; and, as we have already seen, they then regarded the presence of 

 ei«ht spiracles in P. melo, besides that in the anal interradius, as due to the effects of 

 much erosion. 



Hi inn rls. In reality, however, it is a perfectly natural condition (PI. VII. figs. 14, 

 15), and the spiracles do not lead into any canals " passing entirely through the 

 (deltoid) plates," as stated by Meek and Worthen, although this actually is the case 



1 Trans. St. Louis Acad. Sci. 1863, vol. ii. no. 2, p. 375. 

 - Report Geol. Survey Illinois, 1806, vol. ii. p. 274. 



3 Proc. Acad. Nat. Sci. Philad. 1861, p. 142. 



4 Except, of course, as regards the mouth of EUiacrinus. 



