Hambach — Revision of the Blastoideae. 59 



This species is easily separated from its nearest relatives, as 

 Crihroblastus sayi (Pentremites sayi of Shumard), by its 

 coarse granular surface . Of this nice unique Blastoid I possess 

 only a silicious cast and mould though sufficiently preserved 

 to recognize its distinction from similar species. 



Geological formation and locality : It was discovered in a 

 cherty rock of the Burlington formation at Allenton, St. 

 Louis County, Mo. 



Cribroblastus tenuistriatus n. s. 

 Plate v., Fig. 16. 



Body small and oval in outline, being a little wider at the 

 summit than at the base. Basals very small but visible in a 

 lateral view. Ambulacra narrow and linear, not extending 

 over the whole surface of the body, occupying only three- 

 fourths of its entire length. Deltoids about one-third of the 

 whole length, the whole interambulacral space rounded and 

 with a lancet-shaped longitudinally striated elevation extending 

 from the base to the apex of the deltoid whereas the deltoid, 

 surface and the surface at both sides of the lancet-shaped 

 elevation are ornamented with little granules arranged in a dis- 

 tinctly transverse manner. Genital openings very small and 

 formed by the junction of the deltoid and lancet piece. Ver- 

 tical diameter one-third greater than the transverse. Whole 

 length of the specimen -j-g- of an inch, width ^V inch. 



Geological position and locality : In the Burlington lime- 

 stone. Cooper County, Missouri. 



Cribroblastus schucherti n. s. 



Plate v., Fig. 8, 8a. 



Body globose, about as broad as long. It is one of the 

 smallest species known. Basal portion very small and de- 

 pressed. Fork pieces narrow, with a narrow sinus for the 

 reception of the ambulacrum extending almost the whole 



