228 E. Billings on the structure of Crinoidea, Cystidea, ete. 
me Crinoids the pinnule are attached to the radial joints of the 
n Pentremites they are not connected with the lancet 
sate but with the pore plates. In P. pyrijormis they appear 
to me to stand in sockets excavated in the suture between the 
pore plates Proper and the supplementary pore plates. Miller 
compared the the series of azygos plates, which underlie 
that portion of. a ambulacrum of Pentacrinus that runs from 
the mouth to the base of the arm. These resemble the lancet 
lates, in their being azygos and not connected with pinnule ; 
ut then, on the other hand, they differ from them in having, 
a portion at least, of the respiratory tubes on their ventral as- 
pect. Mr. Rofe says that, “in many species of Pentremite, if 
not in all, this lancet Res is in reality a compound plate, 
formed of two eer lates, extending from the bottom of 
sum eke gee gs, mae pass down the adjoining sinus, to ees 
e 
1. M 
P. obesus (Lyon and Cassiday) which was given to me by Mr. 
Lyon, a polished section shows that one of the lancet plates is 
thus divided, but in general no trace of a suture can be seen 
in these plates. 
to have been exclusively ee by the ovarian res sends 
off branches, right a eft alternately, iowa! the sides of the 
ambulacrum. Thess branches do not run directly to the am- 
bulacral pores. Each of them terminates at a point between 
the inner extremities of two of the pores. There is at this 
cag a small pit which appears to be the socket of an append- 
e quite distinct from the pinnule. The groove does not 
pinnules, there pds id other rows of appendages on 
pe - e of the median gro 
eneral i a hich I have arrived from 
shaved are, that all the sietodigal slate that compose the shell 
