64 NEW YORK STATE MUSEUM 



and consider that, in view of these differences, it would be mislead- 

 ing to unite the form here described with Miospondylus, especially 

 until the characters of that genus still in doubt have been cleared up. 



Klasmura mirabilis nov. 



Plates 20-22; plate 23, figures 1-7 



The Naples beds (West Hill flags) of the Deyo Basin near 

 Naples have afforded to Mr D. Dana Luther, an abundance of ray 

 fragments of an auluroid, besides numerous crinoids and several 

 species of a Urasterella. This Devonic ancestor of the brittlestar 

 was so brittle that, though we counted hundreds of rays and 

 fragments of rays, there were only two disks found, one with no 

 rays left and the other with but two fragmentary rays remaining. 



Description. Specimens small, largest ray (fragmentary) 

 observed, 41 mm long and 3 mm wide; disk circular, small (one 

 4.5, the other 6 mm in diameter). Rays slender, flexuous and 

 extremely brittle ; flat or slightly concave on the actinal side and 

 with a median crest bordered by flatter margins on the abactinal 

 side. Dorsal plates (dorsal sides of thickened ambulacrals) occupy- 

 ing about one-half of width of ray; separated by median groove 

 with fine central suture; somewhat bifurcated at distal end; the 

 outer prong developing into a longer spoutlike process. Ambulacral 

 ossicles elongate, boot-shaped, the " shaft " straight and about as 

 long as the " foot" or longer (see pi. 22, fig. 1) ; about thirteen 

 to 'fifteen in 10 mm in the proximal portion of rays. The variable 

 aspect of the ambulacrals in the specimens (see pi. 22, fig. 5, 

 8; pi. 23, fig. 3) shows that they were on the ventral side dis- 

 tinctly fused, leaving but a slight depression in the median line 

 (pi. 23, fig. 3). The ambulacral canal was well inside. On the 

 lower surface, also the foot or wing and the " body " of the 

 ambulacrals were separated by distinct grooves (see pi. 22, 

 fig. 5), giving the impression that these ossicles consisted of two 

 bars, a longitudinal and a transverse one. The median furrow is 

 covered by a series of oval, thick (conical) ossicles, the ventral 

 plates, which are broadest distally and not in contact with each 

 other, leaving small interspaces (see pi. 22, fig. 8; pi. 23, fig. 4). 

 They are mostly lost (pi. 22, figs. 5, 6 etc.) exposing the suture of 

 the vertebral ossicles or even the ambulacral channel, where the 

 ray is slightly weathered (see pi. 22, fig. 6). 



The side plate consists of a flat subquadrangular body, bearing a 

 prominent crossbar which connects with the wing of the -adjoining 



