40 Revieivs — Wachsmiith Sf Springer's Monograph on Crinoids. 



of Dendrocrinus and Poteriocrinus makes rt descend into the cup 

 with no disturbance, but with the development of a new plate, 

 which both in Poteriocrinus and Gyathocriniis occupies the position 

 formerly occupied by rt and by the proximal median tube-plate of 

 Merocrinus and locrinus. A similar process is shown by their 

 drawings to have taken place on the left, though to a less extent. 

 This " disturbance " is a mere bogey : if x did sink, it did not slide ; 

 it gradually grew downwards at its lower margin, as the basal and 

 radianal grew upwards to meet it, and as it gradually became 

 resorbed at its upper margin ; and the adjacent plates were not 

 disturbed, but all sank along with it, as has been shown. If 

 " disturbance " is not all nonsense, then take a tube fixed at one 

 end and " composed of five longitudinal rows of hexangular [sj'c] 

 pieces, alternating in adjoining rows," and intercalate a sixth row. 

 Trj'^ with bits of card. You cannot do it without "disturbance"; 

 one at least of the adjoining rows must be raised or lowered. So 

 that this " introduction of a new row of plates " eifects the very 

 change that it was designed to avoid. 



These rather polemical arguments are introduced to show that 

 Wachsmuth and Springer have neither disproved my hypothesis nor 

 proved their own. What they have done is to show that the facts 

 at present known do admit of more than one interpretation from 

 the ordinarily accepted morphological standpoint. They might have 

 adduced the additional argument that the gap between the supposed 

 position of x above the radials and its position between the radials, 

 almost coincided with the gap between Monocyclic and Dicyclic 

 Inadunata. Merocrinus is the only Dicyclic genus of the former 

 group ; Belemnocrinus and Missouricrimis, the only Monocyclic 

 genera of the latter. This of itself is enough to justify a cry for 

 further facts. 



The third conclusion of my 1890 paper is one that I have long 

 since (1892) admitted to be non-proven. Nevertheless our authors 

 deem it worth while to devote considerable space to a discussion of 

 it, in the course of which they evince as much ignorance of their 

 own writings as of mine, and a strange disregard of facts. The 

 conclusion was " that x originated as a plate morphologically cor- 

 responding to an ordinary brachial," and it was suggested that the 

 median row of tube-plates, or mid-rib, of the anal tube of Merocrinus 

 and locrinus, represented a series of modified brachials (IIBr), up 

 which the ventral perisome around the anus had extended. 



The rejection of this hypothesis does not involve the denial of the 

 previous conclusion as to the place of origin of the proximal tube- 

 plate, though my critics persist in confusing the two. Their only 

 serious argument is the impossibility of reconciling my hypothesis 

 with the (alleged) homology between the mid-rib of the locrinus 

 tube and the median anal series of Camerata, an argument sufficiently 

 discounted by the impossibility of proving the homology in question. 



On the other hand, various facts concerning the anal tube of 

 Inadunata, some of which have come to my knowledge since 

 I first propounded this hypothesis, warn us not to reject it too 



