220 



Prof. J. W. Gregory — Fossil Echinoidea 



Affinities. — This species is most nearly allied to a specimen, 

 described by Gantliier as Diplopodia semamensis, Gauth., from the 

 Cenomanian of Jebel Seniama in Southern Tunis, to which it is 

 certainly a near relation. Gauthier referred to the abnormal 

 characters of what he truly described as this " remarkable species." 

 He had only one imperfect specimen ; its dimensions are diam. 85mm., 

 height 12 mm., and diam. of peristome 11 mm. 



A. huinei differs from A. semamensis (Gauth.), as that has more 

 abundant interambulacral tubercles. 



Family PEDINIDiE. 



MICROPEDINA, Cotteau, 1867. 



MiCROPEDINA BIPATKLLIS.' (PI. X, FigS. 4, 5a-f.) 



Test, the average size for this genus ; well rounded, subspheroidal, 

 but with depressed actinal surface, tumid ambitus, and the upper 

 surface much more raised and tapering than the lower. 



Circular in section. 



Apical area and peristome both small. 



Ambulacra : the epipodia appear conspicuously biserial, especially 

 near the mouth, but at the ambitus they may be recognized as 

 triserial. 



The ambulacral plates on the ambitus consist of a large primary, 

 with small adoral and aboral deiniplates ; the aboral and middle 

 epipodia are in the same vertical line, near the interradius ; the 

 adoral epipodium occurs at about the middle of the lower edge, 

 giving the biserial aspect to the ambulacrum. 



Near the peristome the aboral plates may be a primary, and the 

 adoral is nearly so. The ambital ambulacral plates are ornamented 

 by two small granules. Intertunbulacra of long narrow plates with 

 an irregular line of very small granules, which may be as many as 

 seven in number. In some plates the line of granules becomes 

 doubled near the ambulacrum. 



^ Having two small plates (or patella) iu the compound ambulacral plates. 



