60 p. H. CAEPEKTEE ON COMATFL^ FROM 



being entirely so, to any one examining the complete skeleton. 

 This concealment of the first radials entirely, and of the second 

 partially, is a peculiar condition which occurs in very few recent 

 Comatulce ; but it is common to Schliiter's three species A. semi- 

 glohosa, A. lenticularis, and A. italica. In A. cBquimarginata, as in 

 the first of these, a small portion of the dorsal surface of the radials 

 is visible where it is slightly upturned at their lower angles. At 

 four of the angles (possibly only three) every two radials are sepa- 

 rated by a minute triangular piece (fig. 4, c) of very variable size, 

 which represents the end of a basal ray. At the other angle, 

 however, and perhaps even in a second (for it is very difficult to 

 decide), this piece is absent altogether, the corresponding basal 

 ray not quite reaching the exterior of the calyx. 



The articular faces of the radials (fig. 4, 6) have nearly all the 

 characters of those of an ordinary Antedon. They are trapezoidal 

 in form and rather wider than high, with a considerable inclination 

 to the vertical axis of the calyx, so that almost the whole of them 

 is visible when the calyx is viewed from above (fig. 4, a). 



The dorsal fossa for the elastic ligament is very large, as in some 

 other fossil Comatulce^ and takes up about |- of the whole height of 

 the articular face. The middle of its upper portion has the usual 

 deep hollow just beneath the great transverse articular ridge. A 

 prominent rim rises from this ridge around the opening of the axial 

 canal, which is thus very nearly in the centre of the articular face. 

 Prom its upper border there proceed two slanting lateral ridges that 

 separate the large ligamentous from the small muscular fossee on 

 each side. There is also a prominent intermuscular ridge that 

 proceeds upwards from the same point and reaches the centre of the 

 ventral margin of the articular face ; this is not notched, as is 

 usually the case, but quite even, and forms a part of the rim of the 

 deep central funnel. 



Height 7 millims. ; diameter 9*5 millims. 



Locality. The Gault at Folkestone. Original in the British 

 Museum. 



RemarTcs. The characters of this species are intermediate between 

 those of A. semiglohosa from, the Greensand ( = Kreidemergel, Goldf.) 

 of Speldorf and A. lenticularis of the Maestricht Chalk. Its re- 

 semblance to the latter species lies chiefly in the marked curvature 

 of the sides of the radial pentagon ; but it is very like A. semi- 

 glohosa in the shape of the centrodorsal and the articular faces of 

 the radials, and also in the upturning of the flanks of their dorsal 

 surfaces above the outer ends of the inconspicuous basal rays. The 

 articular faces, however, are less hollowed than in A. semiglohosa, 

 so that their opposed edges stand out less prominently than in this 

 species ; bat these faces have a much more marked inward slope, 

 the dorsal fossa for the elastic ligament being visible to a greater 

 extent, when the calyx is viewed from above, than in either of the 

 two allied species. The relative proportions of the calyx also are 

 different from those which obtain in nearly all the other fossil 

 Comatulce. 



