19B Miscellaneous. 



with Scutella and Echinarachnius in opposition to Scaphechinus ; 

 but a shallow impression in the middle line of the interambulacral 

 spaces forms a slight indication of the difference of level in Arach- 

 noidesy which Scaphechinus resembles in this respect. 



The anal orifice in many Scutellce, although situated on the lower 

 surface, is yet quite close to the margin (e, g. in the Miocene >S^. suh- 

 rotunda, Lamk.) ; and Agassiz, in characterizing this genus, in 1847, 

 in his ' Catalogue raisonne des Echinides,' says, " Anus marginal or 

 inframarginal ;" so that we should not be justified in establishing a 

 new genus only because the anus is removed quite into the margin : 

 but it is nevertheless remarkable that our Scutella precisely agrees 

 -with Echinarachnius and Scaphechinus (both of which belong to the 

 present period and to the temperate zone) in the position of the anus, 

 in opposition to all the Tertiary Scutellce with which we are ac- 

 quainted. Consequently, whilst Echinarachnius, notwithstanding 

 its simple ventral furrows, is closely allied to the Scutellce through 

 Scaphechinus and Scutella japonica, the existing tropical genus 

 Arachnoides, Ag. (the only species of which, A. placenta, Linn., I 

 have collected at Timor), remains further removed from them, not 

 only by the acute margin, the position of the anus above the margin j 

 and the elevation of the ambulacral zones over the interambulacral 

 spaces, but also, as Prof. Bey rich indicated to me, by the remark- 

 able retrogression of the interambulacral plates upon the lower sur- 

 face, inasmuch as these (leaving out of consideration the innermost 

 circle, nearest to the mouth) occur only at the margin, and of small 

 and unequal size. The short description of Scaphechinus mirabilis, A. 

 Agass. (Proc. Acad. Nat. Sci. Philad. 1863, p. 359), contains nothing 

 contradictory to our species, except the comparison with Arachnoides 

 with regard to the difference of level between the ambulacral and 

 interambulacral spaces : I am therefore inclined to regard that spe- 

 cies as most nearly allied to mine ; and Scaphechinus (as also Echi- 

 narachnius) as a subgenus of Scutella, the characters of which, oc- 

 curring more prominently in the only species hitherto known, pass 

 through Scutella japonica into those of the genus Scutella. 



2. Nucleolites epigonus, n. sp. 



Shell flat, oval, covered with uniform (spinigerous) tubercles, each 

 of which is surrounded by art impressed space. Lower surface 

 slightly concave ; buccal orifice near its middle (at y^yths of the 

 length), elongate-oval, its margin turned inwards, smooth ; no trace 

 of an ambulacral star round it, except that the direction in which 

 the ambulacral zones run may be detected in the arrangement of the 

 tubercles and in scarcely perceptible depressions of the surface. 

 Anal orifice elongate-oval, situated in the inflated posterior side of 

 the Urchin, nearly vertical, only a little inclined upward, above the 

 margin, but not extending upon the dorsal surface ; a short, broad, 

 channel-like excavation passes from it to the inferior margin, i^m- 

 bulacral plates uniformly narrow, not closed, reaching half the dis- 

 tance between the vertex and the periphery, the two posterior ones 

 ,a little longer; in these also it may be more distinctly seen than in 



