276 



ECHINODERMATA— ECHINOZOA 



PHYLUM IV 



Amb straight, broad at the ambitus ; pore-pairs uniserial and in simple series 

 near the apex, in arcs of from four to seven pairs near the larger tubercles, 

 crowded and polyserial actinally. lAmb with two vertical rows of primary 







Acroddaris nobilis As. 



Fic. 386. 



Upper Jura ; St. Sulpice, near Loole, Neuchatel. ^1, Dorsal view, B, Ventral view. 

 C, Spine, Vi- D, Three compound Amb plates, enlarged. 



tubercles ; only the largest are perforate and crenulate. Spines cyclindrical, 



often tricarinate. Upper Jura and Cretaceous. 



Goniopygus Agassiz. Apical disk large, plates more 'or less ornamented ; 

 oculars insert, genital plates punctured on adoral margin. 

 Peristome very large, with small branchial incisions. 

 Cretaceous and Eocene. 



Glijpticus Ag. (Fig. 387). Amb straight, and narrow 

 except at the peristome, where the poriferous areas are 

 expanded ; with two vertical rows of small, smooth, primary 

 tubercles. lAmh tubercles replaced abactinally by warty 

 or irregular elongate elevations. Epistroma much developed. 

 Abundant in Upper Jura. 



Pig. 387 



Family 2. Aspidodiadematidae Duncan. 



<'»!ivfi'''us Merogiigih- Amhulcicral plafes simple. Coronal plates thin, not imbri- 



icns Goldf. Coral Ras ■ r, r 



(Giyptician) ; Fringeii, eating. Bttsc of cowna resovbed. Oculars all exsert, or all may 

 1- j^ insert. Peristome with ten large primordial ambulacral 



plates. Lantern erect. Lias to Recent. 



Orthopsis Cotteau. Amb much narrower than the I Amb, straight, and with 

 numerous pairs of pores in straight series. Amb with two, lAmb with several 

 vertical rows of small, plain, perforate tubercles. Jura and Cretaceous. 



Eodiadema Dnncan. Lias; England. Echinopsis Ag. Eocene; Europe and 

 Egypt. Aspidodiadema A. Ag. Apical disk very large, oculars insert. Recent. 



Family 3. Centrechinidae Jackson (Diadematidae Peters). 



Ambulacral plates, compound. Coronal plates not imbricate {Mesozoic), or more 

 or less imbricate (Becent). Base of corona resorbed. Oculars exsert, or one to all 

 insert. Feriproct more or less plated, to nearly leathery. Peristome with ten 



