cl.\rk: new blastoids and brachiopods. 371 



IMeek devoted only a couple of lines to the description of Pentre- 

 mitcs siibconoidciis, and placed them in a footnote. The description 

 follows : — " A very small obconic species, much produced below 

 the pseud-ambulacral areas, which are very short, or almost confined 

 to the summit, as in Cadaster, though it is a true Pentretnite." Ham- 

 bach, in 1903, considered this form to be the young of Pentremitcs- 

 pyriformis ("Pentremitcs suhconoideus, Meek, a young form of Pen- 

 tremitcs pyriformis") though he gave no reason for this statement. 



The specimens from which Meek described the species came from 

 the Carboniferous at the Divide between Ross Fork and Lincoln 

 Vallev, Montana. 



Pentremites symmetricus Hall 



Pejitremites symmetricus Hall. Meek, Rept. U. S. geol. survey, Montana, 

 Idaho, Wyoming, and Utah, 1873, p. 469. 



After listing the species from the Carboniferous of Old Baldy, 

 Montana, Meek wrote "As far as can be determined from the speci- 

 mens, it seems to agree well with Pentremites symmetricus." 



SCHIZOBLASTUS HAYNESI, Sp. nOV. 



Plate 1, fig. 15-20. 



Description. — Body small, spheroidal, the greatest diameter exactly 

 in the middle. Basal portion flat, no suggestion of concavity. Sum- 

 mit flat, its diameter rather less than half the maximum thickness of 

 the body. The basal plates are nearly flat (maximum width three 

 millimeters), ornamented by clearly defined ridges running parallel 

 to the sutures. The radials are long, extending nearly the whole 

 length of the body in side-view, ornamented, like the basals, by ridges 

 which run parallel to the base, but diverge somewhat from their 

 mutual suture; the ridges are occasionally interrupted so as to re- 

 semble rows of nodules. The diverging ridges on the interambulacral 

 area occupy a leaf-shaped space, between which and the ambulacra 

 are flattened linear areas ornamented by obscure low transverse 

 ridges; this area rises next the ambulacra to a sharp ridge especially 

 at the lower end where it is ornamented by a row of nodules rising 

 from the side next the ambulacra and crossing over to the leaf-shaped 



