NO. 3 CASSIDULOID ECHINOIDS — KIER 83 



developed, phyllodes double pored, slightly broadened, with two series 

 of pore pairs in each half -ambulacrum; 8 to lo in each outer series, 

 3 to 5 in each inner ; no buccal pores. 



Comparison with other genera. — Pygorhynchiis is very similar 

 to Pygaulus, and probably closely related. Both genera have similar 

 petals, an oblique peristome, phyllodes with approximately the same 

 number of pore pairs in each series, and a longitudinal periproct. 

 They differ in that the test in Pygorhynchiis is generally lower, the 

 anterior margin blunted, posterior pointed, and the sides not parallel 

 as in Pygaulus, but diverging posteriorly. The periproct in Pygo- 

 rhynchiis is usually more marginal. 



Pygorhynchiis is also quite similar to Parapygus, from which it 

 is distinguished by its double-pored phyllodes and its lack of buccal 

 pores ; as opposed to the single-pored phyllodes with buccal pores of 

 Parapygus. As both these features in Pygorhynchus are more primi- 

 tive, and as this genus occurs earlier in the Cretaceous, it is probable 

 that Pygorhynchus is an ancestor of Parapygus. 



Remarks. — Cotteau (1890, pp. 55, 56) says that the apical system 

 is monobasal in Pygorhynchus. This error is probably due to the 

 large central madreporite which gives the apical system the appear- 

 ance of being monobasal. 



As the phyllode structure has not been illustrated in most of the 

 species of Pygorhynchus, I include a drawing of a phyllode of each 

 of the following species: P. minor (Agassiz) (text fig. 66), P. 

 cylindricus (Desor) (text fig. 67), P. valdensis (De Loriol) (text 

 fig. 68 — drawing of the lectotype, herein designated, figured by 



Figs. 66-72. — 66, Pygorhynchus minor (Agassiz) : Phyllode of ambulacrum I 

 of specimen in Ecole National Superieure des Mines, Paris, from Ste. Croix, 

 France, X 10. 67, Pygorhynchus cylindricus (Desor): Phyllode of ambula- 

 crum I of specimen in £cole National Superieure des Mines, Paris, from the 

 Lower Cretaceous (Aptian) at Le Bimet, France, X 10. 68, Pygorhynchus 

 valdensis (De Loriol) : Phyllode of ambulacrum II of De Loriol's (1873, pi. 16, 

 fig. 2) figxired specimen and lectotype in the De Loriol Collection, at the Museum 

 d'Histoire Naturelle, Geneve, Switzerland, from the Lower Cretaceous (Valin- 

 ginian) at Ballaigue (Vaud), Switzerland, X 10. 69, Pygorhynchus subinferus 

 (Desor) : Phyllode of ambulacrum IV of De Loriol's (1873, pi. 18, fig. 9) 

 figured specimen in the De Loriol Collection at the Museum d'Histoire Na- 

 turelle, Geneve, Switzerland, from the Lower Cretaceous (Valanginian), at 

 Ballaigue (Vaud), Switzerland, X I5- 7°> Pygorhynchus obovatus (Agassiz) : 

 Phyllode of ambulacrum III of specimen in the Lambert Collection, Sorbonne, 

 Paris, from the Lower Cretaceous (Neocomian) at Venoy, France, X I5- 

 71, Pygopistes coquandi (Cotteau) : Phyllode of ambulacrum III of the lectotype 

 of Pygopistes excentricus (Gauthier), herein considered a synonym of P. co- 

 quandi, from the Cretaceous (Cenomanian) at El-Aieicha, Tunisia, in the 

 Museum National d'Histoire Naturelle, Paris, X ^S- 72, Hypopygurus gaudryi 

 Gauthier: Phyllode of ambulacrum III of lectotype in Museum National 

 d'Histoire Naturelle, Paris, from the Cretaceous (Cenomanian) at Dj Cehela, 

 Tunisia, X 5- 



