SMITHSONIAN INSTITUTION 
Family RHODOCRINIDAE Roemer 
This dicyclic family, similar to the Dimerocrinidae except that the radials 
are separated all around, is introduced to receive a number of peculiar forms 
falling within its limits for which it has been necessary to propose new genera. 
Paragazacrinus rotundus new genus and species 
Plate 4, figs. 1-4 
On account of the strong resemblance of the tegminal parts this small 
species was at first supposed to be a variety of Gazacrimis ; but when it was 
found that in three good specimens the RR were separated all around by iBr 
truncating all 5 BB that interpretation became untenable, and there seemed no 
recourse except to place it as a new genus under the Rhodocrinidae. There are 
5 IBB sunken in an indented pit, and 4 or 5 large iBr in the cup separating the 
rays up to the tegmen, which branch and become free on the first IIBr, giving 
10 arms in all, which are not further known. The}^ rest in grooves bounded by 
ridges forming a ventral pyramid which is surmounted by an elongate spine. 
This is supported by 5 tegmen plates, the exact relation of which is difficult to 
determine, but they are thought to be interambulacral in position. The three 
rotund calices are figured, together with a detached central spine, as to which 
the question remains open whether it may not belong to Ga.zacrinus, although 
it is believed that the spine is a separate element covering the pyramid. The 
two forms are from the same locality and formation, but whether from the 
same layer is not known. 
Horizon and locality. Laurel limestone, Niagaran ; St. Paul, Indiana. 
Paulocrinus biturbinatus new genus and species 
Plate 4, figs. 5, ga-c 
This genus and species are proposed for the reception of a solitary calyx, 
which both in general form and in cup structure is totally unlike any other 
known from the Silurian. It is large, robust, with truncate conical cup spread- 
ing to the arm-bases, and from there contracting to an opposite cone consisting 
of a manv-plated tegmen passing into a large, subcentral anal tube. The calyx 
plates are thick and strongly elevated, those of the tegmen rather nodose, and 
those of the cup more or less acuminate, and ornamented by radiating ridges. 
The most peculiar thing about this form is the base, forming the truncate end of the 
dorsal cone. There are 5 IBB surrounding an enormous lumen, and no two of them alike, 
3 smaller and pentagonal on the posterior and left posterior sides ; the other 2 hexagonal and 
truncated by BB are larger than the former 3 combined. A similar inecpiality pervades the 
BB but reversed in position as if compensatory, the two larger being the posterior and left 
posterior (see diagram, fig. 5r). Also the RR are more or less unequal, and asymmetric in 
