I20 SMITHSONIAN INSTITUTION 



PLATE LVII 



(All ficures natural size except where otherwise stated) 



^ ° PACE 



Figs. i-io. Taxocrinus colletti White 3g8 



(Also on Plates XXI, LVI) 



(All specimens more or less flattened) 



Fig. I. Very mature, perfect crown with stem, having stem markings and arcuate sutures finely 

 preserved ; left anterior view. 



2. Similar specimen showing distinct stem ossicles studded with beads ; posterior view, with 

 anal tube, and marginal perisomic plates at right side. 



3a. Mature crown, anterior view; with surface well preserved, showing pustulate ornament, 

 and plated perisome intact above distal margin of iBr plates. 



3b. The surface markings, enlarged. X 2. 



4. Specimen with less perfect surface, posterior view ; showing form of post. B and adjacent 

 plates free from anal tube. 



S- Mature specimen, posterior view ; with 1. post, ray removed, showing lateral sutural face 

 of iBr adjoining it; also exposing left side of posterior basal, with lower plates of 

 anal tube resting in socket half way down the plate, and marginal perisome at the 

 right. 



6a. Similar specimen, dissected by removal of 1. post, ray and part of right, showing remnants 

 of tegmen underneath. The post. B with base of tube resting in its socket, and articu- 

 lating margin of iBr to the left, are well shown. The removed parts are shown in 

 accompanying figures. X 2. 



6b. Part of r. post, ray of same specimen, ventral view, from axillary IBr upward; to show 

 especially the longitudinal depression along the margin of brachials for attachment of 

 perisome, commencing about the first secundibrach, or at the level of the last iBr. X 2. 



6c. L. post, ray of same, lateral and ventral view. Shows left lateral articulating face of 

 IBrs meeting the iBr exposed in fig. 60; also longitudinal parallel grooves upon 

 inner suface of plates passing to a more prominent median groove in the free arras; 

 distal part somewhat displaced in the specimen, and brought into line here. X 2. 



6d. Radial and two IBr from fig. 6c, showing opposite, or right lateral, face next to anal 

 interradius. Note the total absence of sutural attachment. X 2. 



6e. Proximal face of radial from same. X 2. 



6/. Distal face of IBrj, detached from same. X 2. 



ya, b, c, d, e, f, g, h. Detached brachials from similar specimen ; to show their form and propor- 

 tions in different parts of ray; — 



7a, IBn, proximal view; b, IBr2, distal; c, IBrs, proximal; d, IIIBr just above axil- 

 lary, distal ; e, f, g, h, higher IIIBr, various proximal and distal views. All X 2. 



8a. Calyx and lower brachials of a specimen entirely free from matrix inside and out; 

 ventral side, with tegmen and arms broken off; showing especially the rounded 

 crescentic distal margin of iBr, curving to meet the rays, and also the rounded margins 

 of both posterior rays. 



8b. Posterior view of same. Shows post. B and socket for support of anal tube, and the 

 rounded right lateral margin of 1. post, ray, with total absence of sutural surface. 



9. A weathered specimen, with surface removed in some parts by erosion. Shows perfectly 

 straight sutures between brachials in those parts, while corresponding sutures in the 

 unaltered parts are sinuous (the so-called " patelloid plates") — proving that the 

 arcuate suture pertains only to the surface. 



loa, b, c. A malformed specimen having 6 rays, and only 4 basals. The rays are irregular, and 

 not all perfectly formed ; and the basals are verj' unequal. 



a. Anterior view. X 2. 



b. Posterior view. X 2. 



c. Diagram showing form and arrangement of plates. 



Keokuk Gr. ; Lower Carboniferous. Figs, i and 2 from Indian Creek, the others 

 from Crawfordsville, Indiana. 



All specimens in the author's collection. 



