GENERA AKD GROFPS OF THE ECHINOIDEA. 115 



Genus GuAMUECRrnvs, JJiuncan Sf Sladen, 1885, Pal. Inch ser. xiv., 

 Monogr. Tert. Ecliin. KacTiJi Sf Kattyioar, p. 82, pi. xiii. 

 fig.. 7, 8. 



Test moderately large, thin, rather depressed, swollen at tlie 

 circular ambitus, conical above, flat and incurved actinally. 



Apical system ? 



Ambulacra witb pairs of pores in triplets, from apex to peri- 

 stome ; plates low, narrow, composed as in the Echinidse ; tuber- 

 cles small, tbe vertical series nearest the pores the largest, in one 

 or three rows, plain. Interradial plates long and low, not twice 

 the height of an ambulacral plate, carrying from one to eight 

 primaries, in vertical rows, the middle row the largest, all slightly 

 larger than those of the ambulacra, imperforate and non-crenulate ; 

 secondary tubercles in lines above and below the primaries and 

 close to the horizontal sutures, forming ridges, with the line of 

 the suture depressed between those of consecutive plates. Ver- 

 tical narrow ridges extending dorsally and actinally from each of 

 the large middle vertical series of tubercles to the transverse 

 edges of their plates. 



Peristome large, rather pentagonal ; ambulacral margins only 

 moderately wide and plain ; branchial incisions distinct, with a 

 raised border. 



Fossil. Miocene: Asia (Kattywar). 



IV. 



The Family Echinometridse and its Subfamilies and Genera. 

 The Family Echinidffi and its Genera. 



VIII. Family Echinometeid^, Grai/, 1855, amendedhy 

 A. Agassiz. 1872, Bevision, p. 423. 



Regular ectobranchiate gnathostomes, with heteropodous or 

 sub-beteropodous tentacles ; test with the long axis not coinciding 

 with the antero-posterior, and the compound ambulacral plates 

 with three or more pairs of pores ; or the test symmetrical and 

 polyporous. Pyramids of jaws with epiphyses ; teeth keeled. 



Subfamily MchinometrincB (p. 116). 

 Large tests, the long axis transverse to or forming small angles 

 with the antero-posterior. Ambulacral plates with from three to 

 nine components, each with a pair of pores. 



