OEXEHA AND aUOUPS OP THE ECHINOIDEA. 67 



Genus Cottaldia, Desor, 1858, Synopsis, p. 113. 



Test thiu, small or moderate in size, tumid, snbliemisplierical 

 or subconical, slightly depressed, circular or subpolygonal in 

 ambital outline, flat and slightly tumid actinally. 



Apical system small, one or both of the posterior radial plates 

 may enter the periproctal ring. Coroual interradial plates very 

 numerous, low and broad. 



Ambulacra narrow ; the poi-iferous zones narrow, slightly 

 sunken, straight, the pairs of pores in simple vertical succession, 

 slightly in arcs actinally ; plates compound, there being three low 

 primaries iu each, with almost straight sutures. Inter poriferous 

 areas slightly tumid, crowded with very small perforate non- 

 crenulate tubercles in horizontal rows, with or without order, and 

 large granules. 



Interradia wide, the low plates with very numerous tubercles 

 resembling those of the ambulacra, placed in a horizontal row on 

 each plate, and with granules nearer the transverse sutures. 



Peristome sunken, small; the branchial incisions small; the 

 interradial lips the largest. 



Fossil. Cretaceous : England, Europe, and N. Africa. 



Recent. ? 



A. Agassiz admits his Cottaldia Forhesiana (' Challenger ' 

 Eeport, p. 182) into the genus with mucb reservation ; and I 

 agree with him that the generic position is doubtful. Cottaldia 

 Carteri, Dune, from the Cretaceous of Eas Eartak, Arabia, must 

 enter the genus Orthopsis. 



II. Subfamily Diplopod i i n ce (p. 59) . 



G-enus DiPLOPODiA, McCoy, 1848, Ann. Sf Mag. Nat. Rist.Her.2, 



vol. ii. p. 412. Desor, 1858, Synopsis, p. 75. Duncan, 1885, 



Quart. Journ. Geol. Soc. vol. xli. p. 443. De Loriol, 1887, 



Faune Cret. du Portug., Ecli. fasc. i. p. 33. 



Test moderate, depressed, circular in tumid ambital outline. 



Ambulacra narrow, with two vertical rows of primary tubercles, 



perforate and erenulate, smaller or nearly equal in size to the 



interradial tubercles ; pairs of pores in double vertical series near 



the apex and peristome, and uniserial at the ambitus ; there is 



much crowding out of the poriferous plates in the biserial parts ; 



at the ambitus there are four primary components to a compound 



plate, or the lowest component may be a demi-plate, the second 



5* 



