ACTTNOCHINIS SEN'ECTl'S, U. Sp. 



Plate I J, V'kj. 33, a'ajijous fn'ilc: Fiij. 24, opposite rieir; Fuj. 25, 



siinniiit. 



Species medium size. t'alyx obpjramidal. tnmeatetl only tlie 

 diameter of the column, transverse section subpentagonal. Radial 

 ridges sharply anguhir. iuterradial plates convex. Diameter about 

 one fourth more than tlu' height, column round. 



Basals form a round cup about three times as \yide as higli. First 

 primary radials large, about as long as wide, tliree hexagonal, two 

 heptagonal. Second primary radials rather less tlian half as large as 

 the first, wider than long, hexagonal. Third primary radials smaller 

 tlian the second, about twice as wide as long, pentagonal, axillary- 

 and bear upon each upper sloping sidi' a single secondary radial. 

 The secondary radials are thick strong iilates and stand out from the 

 calyx. There are ten ambulacral openings to the vault. Arms un- 

 known. 



The interradial areas connect with the vault, and the phites gradu- 

 ate into each othor. They are not uniform, and the jjlates vary in 

 the regular areas from five to seven. In one area, tlu>re is one jjlate 

 followed by two, in the second range, and two in the third I'ange. in 

 another area, there are three plates in the second rangi-. and above 

 which there are three more. The azygous area is very large and con- 

 tains fifteen large plates. 'J'he first one is in line with the first pri- 

 mary radials and somewhat smaller t ban either of lliem. Tt is fol- 

 lowed by two plates in the second I'ange. three in the third range, 

 and five in the fourth range, above which there are four plates that 

 may be classed in this area, though they interlock with those belong- 

 ing to the vault. 



The vault is de[)ress(^d convex and covered with a few very large 

 tumid ])lati'S. The central plate is large and surrounded by seven 

 large ))lates. The azygous t)rifi('e is outside of the circle of seven 

 plates. The plates over the ambulacral channels are lar<.;(' and those 

 in the slightly concave iuterradial areas smaller. 



The species is congeneric with .Ictiiincriinis rlioiitcdiieiisis, nud 

 neit her of them are typical Arliniicriiins. The calyx is that of an 

 . l(7/;/o('/'/;///.s-. and the\ault is more like that of an .\</(iric()criiiiis. 

 I'lider these circumstances, we think they shoukl be referred to 

 Actinocrintis, as the differences are not sutficient to cause them to be 

 referred to a new genus. They do not belong to Fliysetocriints even 



