Beviews — Wachsmuth Sf Springer's Monograph on Crinoids. 43 



between them. In Uintacrinus some pinnules (which are only 

 lesser arm-branches) are so modified by this incorporation that they 

 have lost their original brachial character almost to their tips. 

 Calamocrinus belongs to a family in which there is as a rnle no 

 anal tube of any consequence; but in this genus the tube is 

 20 mm. long and 5 mm. in diameter half-way up, and, according 

 to Alexander Agassiz, it was " for more than half its length rigiilly 

 soldered to the edge of the adjacent arm and pinnule joints." ^ The 



Fig. 19. — Calamoerimis Biomedece. 



I. Posterior view of cup, showing attachment of anal tube to pinnules and proximal 



br.ichials. ( x f , from pi. iii, fig. 3.) 



II. Eadial and proximal brachials seen from inside of cup, showing attachment of 



interbrachials. (Much enlarged, and combined from pi. iii, fig. 6, and pi. xx, 

 fig. 2.) 



III. A similar portion seen from the side, showing the interbrachials (unshaded) 



attached to the brachials and pinnulars (shaded). (Enlarged, from pi. iii, fig. 5. ) 

 All after AI. Agassiz. As, anus ; B, basal ; IBr, primibrachs ; iBr, inter- 

 brachials ; pn, pinnulars. 



food-grooves of the pinnules involved enter the tegmen at some 

 distance from the bases of the pinnules, and thence pass to the 

 mouth. Thus half the pinnule supports a food-groove with 

 associated organs, while the other half supports an anal tube 

 (Fig. 19). We have only to suppose the attachment of the tube 

 to the first pinnule of the right posterior arm for a greater distance, 

 and we should see a state of things almost precisely similar to that 

 which, on my hypothesis, was the case in locrinus. 



There is, then, no difficulty, morphological or physiological, in my 

 hypothesis. But it will not be proved until there be found an 

 ancestor of the Heterocrinidae with the mid-rib of the anal tube 

 free at its distal end and grooved. To such a condition that 

 otherwise incomprehensible structure, the anal appendage of 

 Thaumatocrinus, may be a partial reversion.^ 



^ " Calamocrinus Diomedce " : Mem. Mus. Comp. Zool. Harvard, vol. xvii, No. 2, 

 Jan. 1892 ; see p. 36. The adjoining figures are adapted from this marvellously- 

 detailed work. 



- P. H. Carpenter, " On a new Crinoid from the Southern Sea" : Phil. Trans., 

 1883, pt. iii, pp. 919-933, pi. Ixxi; see pp. 925, 930. 



