BihliograpMcal Notices. 287 



interradial and its cirri radial, and it is therefore " built upon the 

 plan of dicyclic Crinoids ;" but the processes of the axial canal are 

 interradial, and not radial as they ought to be according to the 

 generalizations on pages 7 and 8, which we have quoted above. The 

 ' Challenger ' Report upon the stalked Crinoids, which was in Mr. 

 Wachsmuth's hands nearly four months before the presentation of his 

 Part III. to the Philadelphia Academy, contains figures which 

 illustrate this point in four recent species of Fentaa-inus, and he 

 would therefore have done well to make sure of his facts before 

 generalizing on the subject. We doubt if there is a single species 

 of Pentacrinus which has a radial axial canal. It is curious, how- 

 ever, that in the closely siuiila]- genus Metacrinus the processes of 

 the axial canal are radial, though no underbasals are present as in 

 Extracrimis. But perhaps the most curious anomaly is presented 

 by the two allied genera Batliycrinus and Rhizocrinus. In the 

 former, as in Pentacrinus, the angles of the top stem-joints are 

 interradial, but so are the processes of the axial canal ; while 

 exactly the reverse is the case in Rhizocrinus^ which, like Apiocrinus, 

 has radial angles to its cirrus-less stem, though the processes of the 

 axial canal are also directed radially. 



All four genera agree, however, in the absence of underbasals, 

 though one of the characters which should be correlated with their 

 presence, together with one which should not, occurs in each type. 



We cannot but wonder that with these facts before them Messrs. 

 Wachsmuth and Springer should have committed themselves to the 

 very positive statement that " the Neocrinoids are built upon the 

 plan of dicyclic Crinoids." 



There is another case of the same kind to which we must allude 

 (p. Q2). They have noticed " narrow grooves upon the inner sur- 

 face of the vault, which meet beneath the median part of the oral 

 plate, and follow the subtegminal galleries which enclose the ambu- 

 lacral tubes ; " and they have reasons for thinking that these grooves 

 and the ridges which correspond to them on the internal casts 

 " do not represent the ambulacral tubes." We will not discuss 

 this point, but pass on to the conclusions which they draw on pages 

 62 and 137 (especially the latter) — " That the grooves are placed 

 along the solid walls of the test, has led us to suppose that they 

 were axial canals (!), and that perhaps in these Crinoids, contrary 

 to others, and to the Neocrinoidea generally, the entire nervous 

 system was located at the oral side, in conformity with other Echino- 

 derms. Our interpretation becomes more plausible when we con- 

 sider that in the Camarata the radials are never pierced by canals, 

 and it would be difficult to understand how these ponderous arms 

 could have moved without axial cords, Tonless their movements were 

 altogether passive." 



"We wonder that the authors do not see that the same argument 

 would hold good for the vault-plates, which are not perforate but 

 merely grooved ; and even supposing their statement about the 

 Camarata to be invariably true, it does not imply, as they assume, 

 that there were no nervous axial cords on the inner surface of the 



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