94 THE FOSSIL ECHINOIDEA 



the usual generic attributes. Another species, not sufficiently well preserved to be 

 diagnosed, is normal in respect of the uniform size of the tubercles. 



The new genus Acanthechinus is not without alliances with Stirechinus, a Miocene 

 or Pliocene form from the Sicilian Tertiaries ; and the singular genera Burypneustes and 

 Molopneustes are unique, although they clearly represent such genera as Micropsis and 

 Orthopsis, which are common in other Nummulitic faunas. But the generic distinctions 

 are very evident. 



The most interesting forms of the Echinoidea in the collection are those which 

 must be temporarily classified amongst the Temnopleuridse. The apical system and 

 ornamentation of the Dictyopleuri separate them from Temnechinus and Temnopleurus. 

 The ornamentation recalls that of Glyphocyphus and Temnechinus lineatus, Duncan, of 

 the Australian Cainozoic strata. It greatly resembles that of the forms classified by 

 d'Archiac and Haime under the genus Temnopleurus, they not being Temnopleuri on 

 account of the absence of true pits at the angles of their sutures. They have not the 

 apical system perfect ; and we range them in our genus Dictyopleurus provisionally, 

 trusting to obtain perfect specimens from higher horizons. 



With regard to Arachniopleurus, it has a considerable range in space, as we have 

 seen specimens collected in Persia and also in Kach. Probably Paradoxechinus of 

 Laube, from the Australian Cainozoic (Tertiary), links our Bictyopleurus to Arachnio- 

 pleurus. None of these forms have the true Temnopleurid penetration and undermining 

 of the test ; in fact, they have greater alliances with Glyphocyphus than with Temno- 

 pleurus ; but the apical system of Glyphocyphus differs. Neither in the Egyptian nor 

 European Nummulitic areas have these remarkably ornamented genera been distin- 

 guished ; and Glyphocyphus belongs to the Upper-Greensand age. 



With regard to the form Progonechinus Eocenicus, we have with some hesitation 

 placed it amongst the Temnopleuridse ; its position in the family depends on the normal 

 nature of the cavities which exist at the angles of the sutures. The ornamentation is 

 totally different from any known genus, however. 



With regard to the forms usually classified under the genus Conoclypeus by palae- 

 ontologists, it must be remembered that Zittel ('Handbuch der Palaontologie,' vol. i. 

 p. 515) has proved that Conoclypeus conoideus, Lamarck, has auricles and jaws, and 

 that de Loriol has shown (' Echinides de I'Egypte,' p. 76 et seq.) that several other 

 so called species of Conoclypeus have not jaws. The possession of jaws is generic, and 

 it is accompanied by an absence of phyllodes, or doubling of the ambulacral pores near 

 the peristome. On the other hand the absence of jaws and the presence of a phyllode 

 take the species out of the genus Conoclypeus. Some of the species formerly classified 

 with the genus Conoclypeus will now, on account of their having a phyllode, small 

 bourrelets, and no jaws, be placed as a new genus, Phylloclypeus, de Loriol. Others 

 are species of Hchinolampas according to de Loriol, such, for instance, as Conoclypeus 

 Osiris, Desor, from Egypt. 



The new forms from Sind are readily distinguishable from the Egyptian types 



