204 ME. P. H. CABPENTER ON THE GENUS SOLANOCRINTTS 



as in A. costata, but a relatively narrower opening* in the 

 form of a star with five blunt petaloid rays. These rays corre- 

 spond to the interradial angles of the calyx, where there is no 

 notch between the muscle-plates of adjacent radials ; but the 

 upper edge of each plate rises considerably from its inner to its 

 outer margin, where it meets its fellow of the next radial (PL X. 

 figs. Via, 18«). The edges of the muscle-plates are here somewhat 

 thickened and everted, so as to produce the more or less petaloid 

 figure surrounding the central funnel (fig. 175). The ventral inter- 

 radial furrows start from the points of the figure and lead down 

 into the interior of the calyx ; the ventral radial furrows, on the 

 other hand, start from shallow notches in the re-entering angles 

 of the figure. These notches separate the inner ends of the two 

 muscle-plates of the same radial, but are not continued down on 

 to the articular surfaces, except as very faint grooves. 



This eversion of the muscle-plates at the top is especially 

 marked in fig. 15 on tab. 81 of Quenstedt's ' Jura,' and in PL X. 

 fig. 18 a; while it is much less distinct in the specimen, from a 

 different locality and horizon, represented in fig. 34 on tab. 51 of 

 the ' Petref actenkunde,' so that the opening of the central funnel 

 is more nearly pentagonal and less distinctly stellate. In this 

 specimen, too, the basals are smaller than usual, though there is a 

 considerable range of variation in this respectf . In some forms 

 they project prominently beyond the level of the radials, the so- 

 called Solanocrinus JBronnii of Minister^ showing this most di- 

 stinctly (PL X. fig. 16). I am disposed to follow Quenstedt's 

 example and to merge this species in A. scrobiculata, the range 

 of variation in which renders the isolation of Minister's species 

 rather difficult. 



The numerous varietal forms which have been referred to A. 

 scrobiculata (and all agree in the characters already mentioned) 

 differ very considerably in the appearance of the outer surface 

 of the radials and in the shape of the centrodorsal. Thus, one 

 of Goldfuss's specimens (PL X. fig. 14) had a very deep centro- 

 dorsal, with the high outer surfaces of the radials much narrowed 

 'below by the large size of the basals. But a Woodwardian 

 specimen with a similarly deep centrodorsal has a calyx with 

 characters intermediate between those of Goldfuss's two varieties 



* The opening of the original of fig. 17 b is both wider and more pentagonal 

 than usual. 



t Compare figs. 15-17, 19 & 21 on Plates X. and XL 

 | Beitrage zur Petrefactenkunde, p. 101, Taf. xi. fig. 7. 



