210 CATALOGUE OF THE BLASTOIDEA. 



Nucleoblastidse, which are perhaps also connected with Granatocrinus through the 

 medium of Heteroblastus (PI. VI. figs. 2-4). 



The division of the posterior deltoid of Elceacrinus into two parts by the intercala- 

 tion of an anal plate (PL XVIII. fig. 19) is such an unusual feature in Blastoid 

 morphology, that we have been led to remove this type from the other three members 

 of the family, and to place it in a subfamily by itself, which we propose to call 

 Elseacrinidae. It must be remembered, however, that superficial markings, indicative 

 of a similar triple division of the interradius, are shown on the other four deltoids of 

 Elceacrinus and often also on all those of Schizoblastus Sai/i, as we have pointed out 

 on p. 35. In this species, and possibly also in S. melonoides, the only other American 

 type which we can definitely refer to this genus (PI. III. fig. 3 ; PI. VI. fig. 16), the 

 posterior spiracles are separate from the anus, as in Elceacrinus (PI. XVIII. fig. 16) ; 

 but those of the Irish species S. Bofei and S. Bailii (PL VIII. fig 9 ; PL XVI. 

 fig. 12) are confluent with the anus as in Oryptoblastus and Mesoblastus (PL VI. 

 fi^s. 7, 8, 13 ; PL VII. figs. 14, 15). In the latter genus, however, the side plates 

 form the distal border of the spiracle, which is not the case in the Nucleoblastidse. 



i. Subfamily. El je acri ni d^, E. & C, 1886. 

 Definition. Posterior deltoid divided into two parts by an anal plate. Anus 

 distinct from the posterior spiracles. 



Genus ELCEACRINUS, F. Eoemer, 1851 (emend. Hall, 1862). 



Nucleocrinus, Conrad, Journ. Acad. Nat. Sci. Philad. 1842, vol. viii. pt. 2, p. 280. 



Olivanites, Troost (MS.), American Journ. Sci. 1849, vol. viii. p. 419. 



Olivanites, Troost (MS.), Proc. American Assoc. Adv. Sci. for 1849 [1850], p. 62. 



Elceacrinus, Roemer, Archiv f. Naturgesch. 1851, Jahrg. xvii. Bd. i. p. 375. 



Elceacrinus, Roemer in Bronx's Lethrea Geogn., Dritte Ann. 1852-54, Theil ii. p. 283. 



Nucleocrinus, Hall, Fifteenth Aim. Report New York State Cab. Nat. Hist. 1862, pp. 144 



and 146. 

 Elceacrinus, Dujardin & Hupe, Hist. Nat. Zooph. Echinod. 1862, p. 100. 

 Elceacrinus (pars), Shumard, Trans. St. Louis Acad. Sci. 1863, vol. ii. no. 1, p. 111. 

 Elceacrinus, Shumard, ibid. 1865, vol. ii. no. 2, p. 368. 



Nucleocrinus, Meek & Worthen, Report Geol. Survey Illinois, 1866, vol. ii. p. 275. 

 Nuclevcrinus, Billings, American Journ. Sci. 1870, vol. 1. p. 229. 

 Eleacrinus, E. & C, Ann. & Mag. Nat. Hist. 1883, vol. xi. p. 228. 



Gen. Char. Calyx ovate-oblong, olive-shaped, or elliptical, usually more attenuated 

 towards the base, but enlarging above the basi-radial sutures with a graceful swelling 

 outline : summit flat, rounded, or slightly concave ; base excavated (except in one 

 species), the calyx supported on the radial lips when in a vertical position; plates 

 usually anchylosed ; section pentagonal, with concave or nearly round sides, and 



