290 ROBERT TRACY JACKSON ON ECHINI. 



The interambulacral plates bear one or occasionally two small eccentric perforate primary 

 tubercles with scrobicules, and scattered secondary tubercles. These are shown best in the 

 Munich specimen (Plate 19, figs. 3, 4). The spines are small primaries and secondaries. From 

 the swollen base they taper to the tip and are longitudinally finely striate. This species is 

 known from two good specimens : the type from the Schultze Collection in the Museum of Com- 

 parative Zoology, and a specimen in the Munich Museum, both figured here. The Munich 

 specimen is especially clear in its surface characters, and the interambulacral plates lie very 

 nearly in horizontal rows instead of alternating in adjacent columns, as usual in Echini. Besides 

 tubercles, it shows a number of spines in place, which are also figured enlarged. Isolated in- 

 terambulacral plates are fairly common in collections. 



Middle Devonian, Gerolstein, Prussia, two fine specimens, the holotype, from the Schultze 

 Collection, Museum of Comparative Zoology 3,040; and one in the Munich Museum. Spines 

 from the same locality, including those figured by Schultze, Museum of Comparative Zoology 

 Collection 3,043. Isolated plates from same locality, Museum of Comparative Zoology 3,042, 

 3,045; British Museum E 1,201; Strassburg Museum; Freiburg i. B. Museum; Pelm, Prussia, 

 Museum of Comparative Zoology Collection 3,103-3,105; Rommersheim, near Prum, Prussia, 

 Museum of Comparative Zoology 3,041. 



*Lepidocentrus whitfieldi sp. nov. 

 Plate 19, figs. 6, 7; Plate 21, figs. 4, 5. 



Lepidechinw rarispinus (pars) Hall, 1868, p. 295 (non Plate 9, fig. 10); 1870 (revised edition), p. 340 

 (non Plate 9, fig. 10); (pars) Jackson, 1896, p. 228; (pars) Klem, 1904, p. 22. 



Test spheroidal, flattened on the base, probably from pressure. Known only from an 

 internal mold. Ambulacral areas narrow throughout, plates low. Eleven columns of small 

 plates in an interambulacral area, the plates strongly rounded in outline. The primordial 

 interambulacral plate is in the basicoronal row, as shown in one area. The oculars, as indicated 

 by an impression, are small, insert; genitals high, with numerous genital pores, nine or ten in 

 the impressions preserved. Professor Hall included this specimen in his Lepidechinus rari- 

 spinus, here called Hyattechinus rarispinus. It differs from that species in that the ambulacra 

 are narrow throughout, instead of broad and petaloid ventrally, as in rarispinus. This differ- 

 ence Professor Hall was not aware of, as he had only the dorsal part of rarispinus (p. 395). I 

 think it also differs in its spheroidal form, as rarispinus is almost certainly highly flattened, 

 (p. 292) but this might well be only a specific, not a generic difference. This species I name 

 in memory of the late Professor R. P. Whitfield of the American Museum of Natural History. 



Waverly Group, Lower Carboniferous, Licking County, Ohio. Holotype, and only known 

 specimen, American Museum of Natural History Collection 6,391. 



