FOREIGN JURASSIC HOLECTYPI. 271 



Holectypus arenatus, Desor. Monogr. des Galerites, tab. 9, figs. 11 — 13. 



The tubercles, although very numerous, are disposed with great regularity ; the miliary 

 granules form continuous horizontal series ; mouth opening small, with rows of oblong 

 granules near the peristome ; in its general form it resembles H. pitnctulatus, Des., 

 and H. Mandelslohi, Des., and is distinguished from these species only when the details 

 of the test are well preserved. 



Dimensions. — Height, four tenths of an inch ; transverse diameter, eight tenths of 

 an inch. 



Formation. — Oxfordien du Canton de Soleure. Very rare. 



Collection. — M. Gressly. 



Holectypus speciosus, Miinster. Syu. Galerites speciosus, Goldfuss, Petref. German., 



tab. 41, fig. 5 a, b. 

 Discoidea speciosa, Agass., Echin. Foss. Suisse, 

 tab. 6, fig. 16. [non.) 

 — — Desor, Monogr. des Galerites, 



tab. 10, fig. 13. {non.) 



Test large, depressed ; the plates of the ambulacral and inter-ambulacral areas very 

 narrow in proportion to their length ; tubercles on the upper surface small and irregularly 

 disposed ; tubercles at the base larger, and arranged in double horizontal rows, closely 

 placed together on each plate ; mouth opening small, peristome decagonal ; anal opening 

 large, pyriform, occupying half the space between the border and the peristome. 



Dimensions. — Height, one inch and a half; transverse diameter, three inches and 

 three quarters. 



Formation. — Kimmeridge Clay of the valley de La Birse, near Lanfon (Greifel) ; 

 Upper Stage of the Calcaire Jurassique de Heidenheim (Wurtemberg). 



Collections. — Count Miinster, M. Gressly. 



