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 



Äcrocidaris nobilis Ag. Upper Jura ; St. Sulpice, near Locle, Neuchätel. .1, Dorsal view, B, Ventral view. 

 C, Spina, i/i. 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. 



Glypticus 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. lAmb tubercles replaced abactinally by warty 

 or irregulär elongate elevations. Epistroma much developed. 

 Abundant in Upper Jura. 



Fia 387. 



Family 2. Aspidodiadematidae Duncan. 



Glypticus hieroglyph- 

 ims Goldf. Coral Rag 

 (Glyptician) ; Fringeli, 

 Switzerland. l/i- 



Ambulacral plates simple. Coronal plates thin, not imbri- 

 cating. Base of Corona resorbed. Oculars all exsert, or all may 

 be insert. Peristome with ten large primordial ambulacral 

 Lantern erect. Lias to Kecent. 



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

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

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



Eodiadema BuncB^n. Lias; England. E chinopsis Ag. Eocene ; Europe and 

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



Family 3. Oentrechinidae Jackson (IJiadematidae Peters). 



Ambulacral plates Compound. Coronal plates not imbricate (Mesozoic), or more 

 or less imbricate {Recent). Base of corona resorbed. Oculars exsert, or one to all 

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



