212 MR. P. H. CARPENTER ON THE GENUS SOLANOCRINTJS 



a mistake, especially if we consider the corresponding conditions of 

 JBourgiceticrinus, PJncrinus, and of Comatula. In the latter group 

 basals may appear externally at some angles of the calyx and not 

 at others. This is the case, for example, in Ant. canaliculata 

 (PI. IX. figs. 6, a, b) and in Ant. complanata (figs. 9 a, 9 b), in 

 the latter of which the basals are somewhat similar to those of 

 P. asteria (PI. XI. figs. 21, a, b). Unfortunately we know of no 

 Comatula with Pentacrinus-like basals which yet do not appear 

 externally. But this is probably only because a view of the under- 

 face of the calyx is so rarely obtained. If this face could be 

 exposed in any specimens of d'Orbigny's Comatulina or Decame- 

 ros (PL IX. figs. 7, 8, and PL X. figs. 10-12), it would doubtless 

 be found that the basals were like those of Ant. complanata 

 (PL IX. fig. 9) and P. asteria (PL XI. fig. 21), only rather 

 shorter and not appearing externally as in these species. This is 

 possibly the case in some of the species figured by de Loriol. I 

 imagine it to be also the case in Isocrinus pendulus, P. Fishery and 

 the other forms with no external basals, though it is, of course, 

 possible that their basals may have undergone transformation 

 into a rosette, as in recent Comatula?. But this seems to me very 

 unlikely. All the evidence we have goes to show that the basals 

 of the Jurassic Comatula? persisted, as in recent Pentacrini, with- 

 out undergoing transformation into a rosette, and it is improbable 

 therefore that this transformation should have occurred in extinct 

 species of Pentacrinus. 



It would be very interesting to determine, were it only pos- 

 sible, how and when the Comatula-stock first began to develope 

 a rosette. As to Ant. costata, Ant. scrobiculata, and Act. chelto- 

 nensis, there can, I think, be little doubt that their basals are the 

 embryonic ones. In the latter species there is obviously no rosette 

 (PL XI. fig. 20 b), and the same applies to Ant. scrobiculata 

 (PL X. fig. 18 b), in which the margins of the under surfaces of the 

 basals are faintly plaited. This feature is more marked in a 

 specimen in the British Museum figured in Konig's ' Icones ' as 

 Symphytocrinus Jlorifer, in obvious reference to the petaloid figure 

 formed by its basals,which expand rather more between their inner 

 and outer ends than do the corresponding parts of the Cambridge 

 specimen. It forcibly recalls the plaiting on the underside of the 

 basals of Pentacrinus, which may be almost separate (PL XI. fig. 

 21 b), completely united (figs. 23, 24), or in an intermediate condi- 

 tion like those oiAnt. scrobiculata (PL X. fig. 18 b) audi Act. chel- 

 tonensis(F\. XI. fig. 20 b). We may therefore, I think, consider 



