Hamhach — Revision of the Blastoideae. 61 



the summit, not confluent, the oblique opening giving a slit- 

 like appearance to them. Anal opening ^ inch below the 

 summit. Poral openings 11 to ^ inch. The greatest trans- 

 verse diameter is at the apex of the ambulacrum, which is 

 about f below the summit. Vertical diameter f and the 

 transverse diameter about f of an inch. 



Geological formation and locality: Warsaw limestone, 

 Boonville, Missouri. 



Globoblastus magnificus n. s. 

 Plate III,, Fig. 5. 



This specimen, although only a silicious cast, differs so much 

 from all other known species, that I am thoroughly convinced 

 of its specific value. It is nearly twice as large as an ordinary 

 G. noriooodi, from which it is readily separated by the fol- 

 lowing characteristics. The base, though small, is not 

 depressed, as in G. norwoodi. Fork pieces resemble those of 

 G. norivoodi, but are larger and reach nearly to the summit 

 of the calyx. The sinus of the ambulacrum is very narrow, 

 extending, as in G. norwoodi, nearly the whole length of 

 the ambulacrum. 



Deltoids, to judge by the impressions of the suture mark- 

 ings, are perforated as in G. norivoodi. This is shown plainly 

 on a small part of a deltoid piece remaining in the cast, 

 which leaves no doubt as to its generic affinities. Interambu- 

 lacral spaces seem to be more rounded and convex than in 

 G. norwoodi. External ornamentation not known. Ambu- 

 lacra narrow and seemingly extending over the whole surface 

 as in the true noi^woodi. The main differences, beside the 

 size, between this species and G. norwoodi, are the shallow 

 depression or almost flat basal plates and the more rounded 

 interambulacral spaces, and, probably, a different external 

 ornamentation . 



Geological formation and locality : In a chert rock be- 

 longing to the same age as the Burlington limestone, in the 

 southwestern portion of Missouri, near the Arkansas boun- 

 dary line. Height of specimen, 1^ inch. Width, 1 inch. 



