31 



directed npwanl. so as to lie wliolly visihlc in ;i suinniit view, lint cjin- 

 not be seen in a basal view. Plates plane ami smooth. No ovarian 

 pores discovered, though oiu' specimens are in a fine state of preser- 

 \Rtion. 



Basal plates form a i-ouiiilrd expandinu euji with a small r-oucave 

 depression for the attachment c)f the column. ]"irst ]iriinary radials 

 large, as long as wide, three hexagonal, two hcptagonal. Second 

 primary radials hexauonal, abfint as lonL;' as wide, and having;' the 

 appearance of tlie seconil primary radials in AvIiiitirrimiA. Third 

 primary radials smaller than the second, the twoadjoing the azygons 

 area hexagonal, the other three heptagonal. and in the ray opposite 

 the a/.ygons area, bears, on each np])er sloping side, two secondary 

 radials, which gives to this ray two arms. In each of the other rays, 

 the third primary radial supports, on each upper side, two secondary 

 radials. the last ones being axillary and bearing, on each upper 

 sloping side, a small tertiar\ radial, which gives to t'ach of these ravs 

 four arms or four small andmlacral openings to the \ault. There 

 are, therefore, eighteen arms in this species. The arm formula is 

 4-1 4+2-1-4+4. 



In eacli regular iiderradial area, there are seven plates, one in the 

 first range, two in the second, twf) in the third and two in the fourth. 

 that sei^arate the arms, and wmU' with the plates of the vault. The 

 azygons area is very larice and contains eiizhteen |)lates. The first 

 one is in line with the first iirimary radials and of about the same 

 size. It is followed by three, in the second ran.ue. five in the third 

 range, five in the fourth range, and four in the fifth range, that con- 

 nect with the jilates of the vault. One of the plates in the last ranire 

 aj)])ears as a small iidercalated plate. 



The vault is roundeil or subhemis|)hei-ieal and [lei-leetiy smooth. 

 There is a large plate at the summit whi<'h is surroundeil \\\- ^^-xk-w 

 somewhat smaller plates, though unee[ual in size. These are sur- 

 rounded by two ranges of smaller plates and a few intercalated ones. 

 There is a small azygons orifice directed horizontally, at the lower 

 part of one of the ])Iates. in the ranj^c of seven, that surrounds the 

 ceidral i)late. 



This is a very peculiar spi'cies. jiartaking of some of the characters 

 of Actinorruiiia ;ind sonu" of the characters of I >(iri/criinis and is 

 referred to the latter, because its affinities seem to be strouLCer in 

 that direction, notwithstanding its smooth vault, than they are with 

 the former. We have two other specimens, which seem to agree 



