234 THE FOSSIL ECHINOIDEA 



Genus PERIPNEUSTES, Cotteau, 1875. 



Test of large or medium size, elongate, inflated, more or less cordiform. Anteal 

 sulcus deep, deeply indenting the margin. 



Ambulacral summit excentric in front. Apical disk compact, with four generative 

 pores. Odd anterior ambulacrum different from the others, formed of small and simple 

 pores. Paired ambulacra petaloid, narrow, very elongate, excavated, nearly equal in 

 length, the posterior pair, however, being sometimes a little longer. Poriferous zones 

 composed, on the apical portion, of small round pores, which become wider, subtrans- 

 verse, and united by conjugating furrows as they recede from the apex. 



Peristome bilabiate, excentric in front. 



Periproct large, oval at the summit of the posterior extremity. 



Tubercles of two kinds, one large, scrobiculate, isolated, confined within the 

 boundary of the peripetalous fasciole, the general tuberculation of the test being 

 crowded and homogeneous. 



Two fascicles : peripetalous and subanal ; the peripetalous fasciole being extensive, 

 angular, and sinuous ; the subanal annular. 



1. Peeipneustes, sp. Plate XXXVI, Figs. 18 & 19. 



Two Spatangoid tests, the preservation of which is unfortunately so very unsatis- 

 factory that even their generic determination is open to doubt, are referred by us to 

 Peripneustes. They are characterized by the deeply indented anteal sulcus; by the 

 long, narrow, paired ambulacra, placed in w'ell-defined grooves ; by the large, isolated 

 primary tubercles confined to the interradia within the boundary of the peripetalous 

 fasciole ; and by the presence of a subanal fasciole. The poriferous zones in the left 

 antero-lateral petal run nearly parallel, and the width of the interporiferous area is less 

 than that of a poriferous zone. The larger primary tubercles within the peripetalous 

 fasciole have small perforated mamelons, subcorneal bosses, deeply crenulate and large, 

 circular, slightly sunken scrobicules. The size of the primary tubercles is irregular, 

 that of the miliary granulation very small and uniform. The peripetalous fasciole is 

 broad and well marked ; it is sharply angulated in the anterior interradia, and is slightly 

 incurved from a straight line between the extremities of the antero- and postero-lateral 

 petals. The subanal fasciole appears to have been very large and probably subreniform 

 in shape. The anteal sulcus is continued, from the ambitus on the actinal surface, up 

 to the peristome, as a well-defined and rather narrow trough ; and the posterior ambu- 

 lacral regions which bound the actinal plastron are very broad and co-jered only with 

 minute granulation. There is a faint gibbosity on each of the plates of the anterior 

 interradia above the ambitus, and indications of a tendency towards a similar structure 

 are discernible in the lateral interradia, but the character is much less developed there 

 than in the anterior interradia. 



As no other observations can be made on the specimens at our disposal, it is 

 obvious that better material is needed before a specific diagnosis can be formulated. 

 The two specimens are from different localities, but we believe that both belong to 



