GEJiTERA AND GROUPS OP THE ECHHifOIDEA. Ill 



spheroidal and depressed, broader than high. Coronal plates 

 numerous. 



Apical system witb a large periproct ; the membrane with 

 numerous plates, which are tuberculate ; ring narrow, genital 

 foramina large ; basal plates broad, pentagonal, the madreporite 

 distinct and in the largest ; radial plates broad, excluded. Coronal 

 plates numerous, low and broad. 



Ambulacra moderate in width ; poriferous zones broad ; 

 tubercles very small, placed near the poriferous zones only, ab- 

 actinally, and closely packed throughout actinally. Median area 

 broad, bare of primary tubercles, with pedicellariae and granules ; 

 poriferous zones broad, with the pairs of pores in very close 

 triplets, appearing to be biserial ; the inner vertical row of pairs 

 of pores the most numerous, formed by the adoral and aboral 

 pairs of a triplet being nearly in vertical series ; the middle pairs 

 of pores are in the outer vertical row, each pair in a demi-plate, 

 which is placed close to the ambulacro-interradial suture. Plates 

 compound, low, broad ; the adoral a large primary, the middle a 

 small demi-plate, and the aboral constituent a small low primary. 



Interradia broad, with a broad, bare, median space, bounded on 

 either side by a belt of several close vertical rows of small tubercles 

 resembling those of the ambulacra ; actinally the tubercles are 

 close and cover the plates. Sutures of the median series 

 finely grooved in both areas ; pits small, at the median angles. 

 Do welling occurs. 



Peristome moderate, decagonal ; branchial incisions small but 

 broad, and with a lip. Perignathic ridges low, processes high, 

 connected, foramen large. Pyramids of the jaws with a small 

 foramen arched over ; teeth keeled. 



Spines small, short, slender ; pedicellariae very numerous. 



Recent. Japan, Philippines, Samoa, Celebes, New Guinea, 

 Sandwich Islands. 



Genus Miceoctphtis, Agassiz, 1841, Monogr. cPEch. viv. etfoss., 

 Preface to Valentin, Anat. Gten. JEch. p. 8. A. Agassiz, 1872- 

 74, Bevisio7i, p. 466. J. Bell, 1880, Proc. Zool. Soc. p. 422. 

 Duncan, 1888, Ann. Sf Mag. Nat. Hist. ser. 6, vol. i, p. 113, 

 pi. xi, 

 Test moderate in size, thick, tumid, prolately spheroidal, or 



depressed, circular or somewhat pentangular in ambital outline, 



contracted actinally. Coronal plates few and very high in the 



interradia. 



