196 



THE CRINOIDEA 



and Pacific (Fig. CXVIIL). FAMILY 5. ACTINOMETRIDAE. Pinnata with 

 dorsal cup and centrodorsal on the Antedonid plan, but differing in the 

 following points: Mouth exocyclic and gut much coiled, with con- 

 sequent larger cavity between RR, small muscle-plates, and facet approach- 

 ing the vertical ; further asymmetry shown in unequal and variable 

 tegminal food -grooves, and in occasional ungrooved structure of some 

 posterior rami, which may be shorter than the rest and without podia ; 

 no sacculi ; no calcified Amb ; proximal pinnules have a terminal serrated 

 margin " comb " ; centrodorsal discoid, with cirri few, almost limited 

 to its margin, and sometimes atrophied. Genus Actinometra, Miiller 

 (1841, em. P. H. Carp., 1887 ; synn. [?] Comaster, L. Agassiz ; Comatula, 



Fio. CXVIIL 



Atelecriiius bidanoides, with two 

 cirri partly preserved and arms 

 imperfect. (From A. Agassiz, after 

 P. H. Carpenter.) x 2 diam. 



FIG. CXIX 



Thaumatocrinus rcnomltis, from the anal 

 side, eta, anal appendage ; u/t, interamlmla- 

 crals ; at, anal tube ; b, basal ; b%, second 

 brachial ; cd, centrodorsal ; t, interradial ; r, 

 radial. (After P. H. Carpenter.) x 



purs; Plumoyenia, Love"n), Lower Jurassic to Recent, almost all seas, 

 littoral to 800 fathoms. Divisible into 8 groups, differing in arm- 

 structure and distribution. FAMILY 6. THAUMATOCRINIDAE. Pinnata 

 with cup of 5 BB forming a closed ring, and 5 RR separated by 5 inter- 

 radials resting on BB ; Br not incorporated in cup ; arms do not fork ; 

 5 0, separated from cup-plates by relatively large iAmb ; no Amb ; no 

 eacculi ; anal tube in post. IR ; post, interradial followed by 5 plates 

 in vertical series forming a free appendage (Fig. CXIX.). Genus 

 Thaumatocrinus, P. H. Carp. (1883), a unique individual, probably young, 

 South Sea, 1800 fathoms. Differs greatly from all other Pinnata; the 

 structure of the cup is as in Xenocrinut (p. 165), the anal appendage is 

 paralleled in some Taxocrini (cf. Fig. XXXVIL). 



