OKAL AND APICAL SYSTEMS OF THE ECHINODERMS. 361 



Echini and the basals of the Pentacrinoid are interradial in 

 their position, while, as I have already mentioned, the so- 

 called first parabasals of Marsujnies are placed radially with 

 regard to the general symmetry of the animal (fig. iii, 2, 2). 

 Consequently, the interradial genital plates of the Urchins 

 (fig. Ill, 3, 3) are compared by Loven, on the one hand, to 

 the interradially placed basals of the Pentacrinoid (fig. i, 

 3, 3), and on the other to the radially situated plates in the 

 first ring of the Marsupites calyx (fig. iii, 2, 2). Both these 

 comparisons cannot surely be correct. Apart from this ques- 

 tion, however, if Loven be right, and the proximal ring of 

 plates in the Pentacrinoid (fig. i, 3, 3) be parabasals and 

 not basals, why does he give the collective name of basals 

 to the " rosette " which results from their metamorphosis ? 

 It is quite impossible to suppose that the homologies of these 

 plates can change during their development, that they can 

 be parabasals in the Pentacrinoid but basals in the adult 

 Comatula. He nowhere tells us what he regards as the 

 basis in the calyx of the Pentacrinoid, but in his descrip- 

 tion of JBhanogenia} a new Comahda from Singapore^ some 

 years ago, he used the expression basals for the pieces com- 

 posing the " rosette " both of Phanoge?iia and of Antedon 

 Eschrichtii, and this, as shown by Dr. Carpenter,^ is the result 

 of the metamorphosis of the five interradial abactinal plates 

 (fig. I, 3, 3) of the Pentacrinoid, which Allman rightly 

 designated basals, but Loven parabasals. 



It is not quite clear what has caused Loven to give up this 

 view (if indeed he has done so) and adopt another which 

 seems to deny the existence of basals in Comatula altogether. 

 For it is impossible that they can be represented by the 

 uppermost stem segment (fig. i, cd), although Agassiz appears 

 to think so, since this develops into the centrodorsal piece of 

 the Comatula, which becomes covered with cirrhi, and in no 

 known Crinoid do these appendages appear upon the 

 *' basis." 



Thus, then, the only hypothesis open to Loven in this 

 case is that the basals of the Crinoids generally, which con- 

 stitute one of the most important elements of their skeleton, 

 are unrepresented in the only larval Crinoid about which we 

 know anything. Nevertheless, plates — the so-called para- 

 basals — which are believed by Loven to be limited ex- 

 clusively, or nearly so, to the Palaeozoic Tessellata, and 

 only to occur in some families of this group, are supposed 



* " Phanogenia, ett hittills okandt slagte af fria Crinoideer." * Ofversigt 

 af Kongl. Vetenskaps-Akademieus rorhaudlingar,' ] 866, No. 9, p. 225. 

 3 ' Phil. Trans.,' loc. cit., pp. 744, 745, 



