THE CRINOIDEA 



149 



FAMILY 5. PISOCRINIDAE. Monocyclica Inadunata with 1. post. R 

 and ant. R much larger than the other RR ; r. post. R is the only 

 compound R transversely bisected, and its lower half separates r. post. Rs, 

 and r. ant. R from BB, and forms with the two large RR the greater part 

 of the dorsal cup. Arms unbranched and non-pinnulate. An anal tube 



1. Pisocrinus. 



2. Triacrinus. 



I.P.V-S/P. T.p.VWr.a. U\ 



PR & PR PR P.R 



ni^^^^Y^ 



iX /l.n.R /;( Dl 1 !/ *Trt.R ) 3. 



PR PR ^ f PR PR 



CalycaiUho- ) 

 crinus. 



- Mycocrinus. 



5. Catillocrinus. 



FIG. LXII. 



Pisocrinidae and Catillocrinidae. PR, pararadials ; t, anal tube plate = x ; R', radianal 

 =RA ; other letters as usual. In ATycocrinus the radianal and lower parts of RR are hidden 

 and therefore represented by dotted lines. 



usually present, resting on post. RR or on their processes. Genera Piso- 

 crinus, de Koninck (1858), Silurian, N.-W. Europe and N. America (Fig. 

 LXII. 1 ; see also XVIII. 5), and Triacrinus, Minister (1839, syn. Tricho- 

 crinus, J. Miiller, 1856), Devonian, Germany (Fig. LXII. 2), differ in that 

 the former has 5 BB, the latter 3. But incipient fusion of BB is seen in 

 P. ollula, and 5 BB occur in some Triacrinus. The anal tube closely 



