LOVENECHINUS. 337 



The type specimen is from the Burlington Group, Lower Carboniferous, Calhoun County, 

 Illinois. It is said to be in the Worthen Collection, now in the University of Illinois, at Urbana, 

 Illinois; same locality and horizon, United States National Museum Collection 33,277; Webb 

 City, Missouri, Museum of Comparative Zoology Collection 3,123 and 3,124; Keokuk Lime- 

 stone, Keokuk, Iowa, a fragmentary specimen, American Museum of Natural History Collection 

 7,245; Boone Formation, Lower Carboniferous, western Arkansas, a specimen collected and 

 loaned me by Dr. G. H. Girty. 



The National Museum specimen of this species is a magnificent individual, one of the finest 

 Palaeozoic Echini seen (Plate 37, fig. 3; Plate 38, figs. 6, 7). Besides having the typical species 

 characters as described, this specimen shows dorsally a few ambulacral plates which are pri- 

 maries crossing the half-area (Plate 38, fig. 7). This is the same feature of dorsal simplicity 

 seen more completely in L. missouriensis (Plate 42, fig. 3). 



In the Museum of Comparative Zoology specimen (Plate 37, fig. 1; Plate 38, figs. 8, 9), 

 the test is spheroidal without compression. It shows the massive character of the plates, the 

 lateral beveling of ambulacrals, and ventrally, as an internal mold in part, an impress of the 

 proximal faces of plates. Another specimen in the same museum (Plate 37, fig. 2; Plate 38, 

 figs. 4, 5) is less nearly complete, but represents a larger individual, the interambulacrum 

 being about 50 mm. in width. It shows clearly surface characters, ambulacral detail, and the 

 thickness of plates. Adambulacral plates are rounded in outline on the internal face of the 

 adradial suture as in missouriensis (text-fig. 244). 



*Lovenechinus missouriensis (Jackson). 



Text-figs. 11, p. 54; 18, p. 59; 221, p. 193; 237, p. 231; 244, p. 338; Plate 39, figs.1-6; Plate 40, figs. 1-3; 

 Plate 41, figs. 1-3; Plate 42, figs. 1-7; Plate 43, figs. 1-5; Plate 44, figs. 1-5; Plate 46, fig. 4. 



Oligoporus missouriensis Jackson, 1896, p. 184, Plate 9, figs. 50-52; 1899, p. 131; A. Agassiz, 1904, p. 

 80; Klem, 1904, p. 38; Fraipont, 1904, p. 11; Lambert and ThieYy, 1910, p. 121. 



This species is represented by a fine series of specimens of various ages. It is largely known 

 from internal or external siliceous molds, but in two examples seen the plates are preserved 

 intact. 



Test spheroidal, somewhat wider than high. The holotype (text-fig. 244) measures 90 

 mm. in height. It is somewhat flattened laterally, and measures through the mid-zone 96 mm. 

 in greatest diameter, and 70 mm. in a plane at right angles to this but in the same zone. A 

 very large specimen, but somewhat compressed (Plate 39, figs. 4, 5), measures about 86 mm. 

 in height and 93 mm. in diameter through the plane J, E, also 90 to 99 mm. in other horizontal 

 planes. If the plates were in place, it would measure several millimeters more. A smaller 

 but quite uncompressed specimen (Plate 44, fig. 2) measures 59 mm. in height, 62 mm. in diame- 



