PALEONTOLOGIC CONTRIBUTIONS 55 . 



Eugasterella Schuchert 



The genus Eugasterella was formerly known as Eugaster Hall. 

 This name being preoccupied by an orthopterous insect, has been 

 changed to Eugasterella. It is thus far represented only by the 

 genotype, E . 1 o g a n i Hall from Hamilton, N. Y. ; a second, 

 Rochester shale type, E. concinnus, that was referred by 

 Ringueberg to the genus, does not belong here according to 

 Schuchert. 



We have before us the genoholotype of Eugasterella, E . 

 1 o g a n i , which is in the New York State Museum, as well as 

 several new species. Since E . 1 o g a n i is based on a single 

 specimen, all discussion of the species, as well as of the genus 

 Eugaster-Eugasterella, has concededly been based on Hall's accu- 

 rate description and diagrammatic figure in the 20th Annual Report 

 of the New York State Museum of Natural History. 



There is no doubt that Hall, on the whole, saw the outlines of the 

 ambulacral and adambulacral ossicles (see pi. 17, fig. 3) quite cor- 

 rectly. He describes the ambulacral ossicles as subquadrate ; this 

 should be qualified into subheptagonal, since, on the inner side the 

 ambulacral gutter forms a zigzag line, thereby producing an obtuse 

 angle of that side of the ambulacral ; and on the outer side the 

 middle of the ossicle is produced into a short truncate process for 

 contact with the corresponding adambulacral, thereby producing 

 two more corners. The adambulacrals are elongate, hammer-head- 

 shaped ossicles with a strong curved to rectangular crest that gives 

 them a crescent-shaped appearance when seen from the actinal 

 side. There are no conclusive marginal spines in the type speci- 

 men, although Hall has figured such. 



We furnish here in figures 3 and 4, plate 17, two drawings of the 

 actinal side of the genoholotype to bring out more distinctly the 

 sculpture of the ambulacral furrow. The outlines of the ambu- 

 lacral plates are not drawn in, because they are not sufficiently dis- 

 tinct. The close similarity or practical identity in the appearance 

 of the ambulacral furrows of this genus with that of Encrinaster, 

 will at once be apparent when the two are compared, and 

 Encrinaster roemeri Schondorf and E . a r 11 o 1 d i 

 Goldfuss could as well be referred to the present genus. We would 

 therefore feel inclined to unite Eugasterella with Encrinaster, if it 

 were not for the fact that wc have two new species of Eugasterella 

 before us which emphasize the differences in habitus between the 



