86 PROF. p. M. DTJNCAlSr's EEVISIOlSr or THE 



the typical arrangement is seen in C. Dehnarrei, Pal. Frang., 

 Terr. Cret. vol. vii. pi. 1140 ; see also O. Foukanense, Peron & 

 Grauth. Foss. de 1' Alger, fasc. 7, pi. vi. fig. 8. 



Grenus Cyphosoma, Agassiz, 1840, Catal. Syst. Ectyp. Ech. p. 19. 

 Besor, 1858, Synopsis, p. 86. Wright, 1869, Pal. Soc, Foss. 

 Cret. Fell. vol. i. p. 128. A. Agassiz, 1873, Iievision,Tp.4<S7. 

 Duncan Sf Bladen, 1882, Pal. Ind. ser. xiv., Foss. Ech. W. 

 Sind, p. 31. Duncan, 1885, Quart. Journ. Qeol. Soc. vol. xli. 

 p. 447. J. Lambert, 1888, Full. Soc. d. Sci. Nat. de V Tonne, 

 1 Semestre. 



Sjn. Phyonosoma, Haime. 



Test moderate in size, tumid at the circular or slightly poly- 

 gonal ambitus, swollen but depressed dorsally and actinally, 

 broader than high. Coronal plates few, their sutures distinct 

 superficially. 



Apical system large, with five basal plates ; the madreporite in 

 the usual plate, and all or some of the radial plates entering the 

 periproctal ring, the posterior basal thrown more or less back- 

 wards and intruding upon the posterior interradium. 



Ambulacra with well-developed poriferous zones, undulating ; 

 pairs of pores diplopodous abactinally, and in arcs of from four 

 to six or more pairs, and more crowded still at the peristome ; 

 plates compound, high, formed of an adoral, a supra-adoral, and 

 an aboral primary component, the other plates of the compound 

 being demi-plates ; the direction of the sutures of the primary 

 plates of the compound is convex towards and on the boss of a 

 large tubercle, the sutures usually being visible on its' flanks. 

 Two vertical rows of primary tubercles. 



luterradia large, with two or more vertical rows of primary 

 tubercles equal to or larger than those of the ambulacra and 

 similar in their constitution, being imperforate and crenulate. 

 Secondary tubercles exist, and small tubercles or granules in 

 large numbers, the median areas often bare for some distance 

 from the apical system. 



Peristome small or moderate ; branchial incisions well marked. 

 Spines solid, long, subcylindrical, aciculate, or spathiform, strai^-ht 

 or bent spoon-shaped, striated or smooth ; milled head and 

 acetabular cuts distinct. 



Fossil. Oolite : Europe. Cretaceous : England, Europe, IST. 

 Africa, Asia. Eocene : Asia. 



i 



