230 PROCEEDINGS OF THE ACADEMY OF [1885. 



state that, notwithstanding we have made the most scrupulous 

 researches throughout our extensive collections and closely 

 examined the descriptions and figures, we have not found a single 

 exception to this rule among all Palaeocrinoidea. There are slight 

 deviations, caused by the quadrangular form of certain columns 

 in species which have otherwise a pentamerous symmetry, but we 

 find this also among the basals, which, when composed of four 

 pieces, cannot be strictly interradial. 



Among Neocrinoidea, our investigations could be extended 

 only to comparatively few genera, as unfortunately these forms 

 have either a round column or a circular canal. Only in a few 

 species of Pentacrinus, Miller ocrinus and Ajriocrinus did we 

 succeed in making out one or the other of these points. In these 

 genera, underbasals are said to be absent, but, curiously enough, 

 the outer angles of the column are interradial, the cirrhi and 

 radiation along the axial canal radial, exactly as in the column of 

 Palasocrinoidea with underbasals, and what is more remarkable, 

 as in Extracrinus, in which, on the contrary, underbasals are said 

 to be present. The latter seems to suggest that probably many 

 Neocrinoidea either possess small underbasals, or these were 

 present in their larval form. This view is strengthened by the 

 fact that underbasals have been found lately in the younger 

 stages of many Ophiurids and Asteroids. 



Prom our observations it is proved conclusively that the under- 

 basals are not developed from the upper stem joint, as had been 

 supposed by some writers, but represent an independent element, 

 as shown by the fact that the longitudinal sections in Crinoids 

 with a quinquepartite column, always alternate with the proximal 

 plates in the calyx. It is also now apparent to us that the under- 

 basals are morphologically of greater importance than has been 

 generally supposed. 



Carpenter's important discovery that the basals represent the 

 genitals, the first radials the oculars of the Echini, and conse- 

 quently that the proximal radial ring of plates in dicyclic Crinoids 

 cannot be basals, has been now generally conceded by European 

 naturalists, while in America it has been accepted only by Prof. 

 Wetherby, Prof. Williams and ourselves, although no objections 

 were urged against it until lately by S. A. Miller. The latter, 

 instead of attempting to prove the falsity of Carpenter's views, 

 makes the singular remark 1 hat the use of the term underbasals, 



