AND ITS RELATIONS TO RECENT COMATUL^I. 213 



it certain that tbe external basals of these Jurassic Comatulce are 

 homologous with those of the larval Antedon and of Pentacrinus ; 

 and I have given reasons above for believing the same to be the 

 case with the forms described as Decameros and Comatulina by 

 d'Orbigny. 



In some, at any rate, of the Cretaceous Comatulce the larval 

 basals appear to have persisted without metamorphosis. In one 

 fortunate case (PI. XII. fig. 30, a, b) a single basal has been pre- 

 served, adhering to the centrodorsal piece; and though its outer end 

 is quite inconspicuous, it is relatively larger than the outer end of 

 the basal ray in either of the recent species represented in PI. XII. 

 There are various other Cretaceous species with larger or smaller 

 basals ; but there are also a few of the Decameros type without 

 external basals, such as Hertha (Antedon) mystica and Act. Loveni. 

 The latter species has such a striking resemblance to recent 

 Actinometrce that I suspect it had a rosette ; and the same may 

 perhaps have been the case with Ant. mystica and with the two 

 Tertiary species Ant. italica and Ant. alticeps. These are the 

 only Tertiary Comatulce of which the calyx is known; but they 

 may, of course, have had concealed Pentacrinus-like basals and 

 no rosette. 



In all recent Comatulce (Comaster perhaps excepted) the basals 

 which appear externally are not the embryonic basals at all, but 

 only additional elements in the calyx*, which become connected, 

 with the central rosette produced by the metamorphosis of the 

 embryonic basals. PI. XII. contains some figures of the calices 

 of a few recent Comatulce, to show these basal rays and their con- 

 nexion with the rosette. They are very well seen in Ant. macro- 

 enema from Sydney Harbour (PL XII. fig. 25 c), which has more 

 resemblance to the Jurassic Ant. costata (PI. IX. figs. 1, 2) than 

 any other recent species. A comparison of fig. 25 c on PI. XII. 

 with fig. 9 b on PI. IX. and fig. 21 b on PI. XI. will show the 

 points of resemblance and difference between the rosette and its 

 appendages in recent Comatulce and the (probably) unmetamor- 

 phosed basals of Pentacrinus and of fossil Comatulce. Pig. 29 b 

 on PI. XII. shows the corresponding parts of Ant. antarctica, 

 in which the basal rays only just appear externally (fig. 29 a). 

 The same is the case in the large Actinometra represented in 

 fig. 26, and in the smaller Act. lineata, shown in figs. 27 a and 

 27 b. These two last figures are very instructive. Pig. 27 b is 

 a view of the calyx from above after removal of three of the 



* Actinometra, pp. 96-101. 



