272 FOREIGN JURASSIC HOLECTYPI. 



Holectypus inflatus, Agassiz. Syn. Discoidea inflata, Agassiz, Echinoderm. Foss. 



Suisse, tab. 6, figs. 4 — 6. 

 — — Desor, Monogr. des Galerites, 



tab. 9, figs. 7—10. 



Test thin, small, and depressed, with tumid, inflated sides ; tubercles small, numerous, 

 twelve rows in the inter-ambulacra, and four in the ambulacra ; miliary granules do not 

 form horizontal series ; mouth opening small and decagonal ; anal opening very large 

 and pyriform, extending from the peristome to the border, with the apex directed 

 towards the mouth. 



Formation. — " Portlandien inferieur (Astartien) du Jura Neuchatelois. 

 "Collections. — Museum of Neuchatel. Coll. M. Gressly." Desor. 



Holectypus giganteus, Desor. Syn. Discoidea speciosa, Agassiz, Echinoderm. Foss. de 



Suisse, tabl. 6, fig. 16. 

 — — Desor, Monogr. des Galerites, 



tabl. 10, fig. 13. 



"A very large, depressed species. The base is furnished with numerous close-set 

 tubercles, but without a regular arrangement ; mouth opening proportionally very small ; 

 anal opening pyriform, hardly occupying half the space between the peristome and the 

 border." 



Formation. — " Corallien de la Vallee de la Birse. 



" Collection. — M. Gressly ; very rare." M. Desor adds, in a note to the above 

 description, in his ' Synopsis des Echinides Foss.,' that it is by mistake this species has been 

 confounded by M. Agassiz and himself with H. speciosus, Miinst. The arrangement of 

 the tubercles is very different in H. giganteus ; the regular concentric disposition observed 

 in H. speciosus is absent in H. giganteus; their regular distribution in the one, and 

 irregular distribution in the other, form a diagnostic character between these two gigantic 

 Holectypi. 



