432 s. goto: 



one (rarely two) central, compressed, acute, mobile spines. The ambulacral 

 spines very small, close, fomieen or sixteen on each ossicule, forming a 

 roimder gi'oup, with two or tlu'ee series of large, scattered, mobile, acute 

 spines on the outer side. 



" This genus reseml)les Stellaster, but differs from it in the oral sm-face 

 l)eing furnished with scattered spines. 



" There is a fossil species very like the one here described foimd in the 

 chalk, and figm-ed in Mr. Dixon's work on the fossils of Wortliiug, which I 

 propose to call CaUiderma Dixonii. There are probably several other fossil 

 species from the same locaHty ; they have been referred to the genus Tosia, 

 but the ossicules are graniüar and the oral surface spinose," 



Ccdliderma emma is then described ['47, p. 193] : 



" Flat, pentangular, the sides concave, the arms elongated, produced, 

 tfiperiug to a fine point, about two-thirds the length of the diameter of tlie 

 disc. The dorsal ossicules six-sided, regular, flat-topped, covered with minute 

 roundish granules ; the central granules of the central ossicules and those 

 down the centre of the arms larger, globular, tubercular-like. The margin 

 sharp-edged, concave in the centre; the ossicules of the upper and lower 

 series alternating, minutely gi-anular, with one or two larger subspinose 

 granules on the middle of the upper margin. Marginal ossicules about fifty 

 on each surface on each side, the lower series with scattered, acute, com- 

 pressed spines on their oral side. 



" The ossicules of the oral side four- or six-sided, rather iiTegular, minutely 

 granular, each armed with a central, compressed, acute, mobile spine. 



"Inhab. ? 



" Tills species most nearly resembles a fossil found in the chalk, which 

 lias hithei-to been refeiTed to the genus Tosirt, and figm-ed in Mr. Dixox's 

 forthcoming work on the fossils of Wortliing. 



" I have named this fine species in compliment to my daughter jNIrs. J. 

 P. G. Smh^h, who before her marriage commenced a series of plates to 

 illustrate a monograph of this genus." 



In his " Synopsis " Gray reproduces the above description with a few 

 trifling verbal improvements ['66, p. 6]. It is not necessary to quote them 



