46 



the fact, tluit tlie first plate abuts agaiust the first tertiary radials 

 and that the second plate is followed by two plates iu the third 

 rauge iustead of oue. 



The vault is couvex, sli.y;hlly depressed iu the iuterradial areas 

 and apparently bears a subceutral proboscis. The plates are an- 

 chylosed in our specimen, and show none of the sutures, and, 

 possibly the hole, which we suppose indicates a proboscis, may be 

 only a hole broken into the vault. There are two orifices be- 

 tween each of the arms that penetrate the vault horizontally. 

 They appi>ar to be excurreut and are of the same character as those iu 

 D. grcdidis, J). Jacifs, D. inarshi . D. steUifer and D. appru.xi- 

 iiiatus. 



This species is so distinct from all others that have been de- 

 scribed, that no comparison with any of them is necessary. 



Found in the Hamilton Group, near Charlestowu, Indiana, and 

 now in the collection of Wm. F. E. Gurley. 



F.\MiLY ACTINOCEINID.E. 



ACTINOCBINUS MONTICULIFEKUS, n. sp. 



I'hitf I \ ', h'ig. 1 . viriv of cal ifx azijguus .side on- the right. 



This is a remarkably large and robust species, the plates are 

 thick and each one bears a more or less ventricose central node, 

 and the larger plates are radiately sculptured toward the margins. 

 The interradial areas arc depressed, giving to the calyx a pen- 

 tagonal outline. 



Basals truncated below so as to have a diameter at the base, 

 equal to about twice the height, they stand upright and are 

 strongly beveled toward the lateral sutures. The middle part of 

 the bas<' has a hemispherical depression for the insertion of the 

 colnmn, leaving a wide flattened rim around the head of the 

 column. First primary radials much smaller than the basals, 

 longer than wide, three hexagonal and two heptngonal. Hecond 

 primai-y radials wider than high, hexagonal and less than half as 

 large as the first. Third primary radials in some of the rays 

 hexagonal, larger than the secoiul, wider than high and support 

 on the superior sloping sides the secondary radials. There is a 

 8iugl(> secondary radial in each series, somewhat smaller than the 

 third primary, wider than high, some heptagonal and others hex- 



