264 PEOT'. p. M. DIIirCAJS"'s EEVrSION OP THE 



Ambulacra diverse, interfered with by the internal fascicle ; 

 lateral petaloid ambulacra flush, with the poriferous zones sunken, 

 with their outer poriferous zones forming a more or less cres- 

 centic tract ; the anterior poriferous zones of the antero-lateral 

 petals nearly transverse, and with pairs of pores more or less 

 aborted within the fasciole. Anterior ambulacrum in the groove, 

 narrow, with small pairs within the fasciole. 



Peristome excentric in front, subcircular or semilunar, the 

 labrum narrow but very long, followed by a small amphisternum, 

 which, with the adjacent broad ambulacral areas, forms a wide space 

 comparatively free from tubercles. Large tubercles, abactinally, 

 varying in number, scrobiculate, crenulate and perforated on the 

 interradia except the posterior; in the thin tests the scrobicule^ 

 form prominent parts (" purses ") within the test, but not or only 

 slightly in thick tests. 



Interradia with the second and third actinal plates of the 

 lateral interradia very large ; and union of the plates 2 and 3 of 

 zone a of the right posterior interradium. Periproct large, in 

 the posterior truncation. 



An internal fasciole crossing the petaloid parts of the antero- 

 lateral ambulacra, and bounding the anterior groove and crossing 

 the anterior odd ambulacrum. A subanal fasciole including the 

 6-9 inner ambulacral plates, tliree or more pairs of pores being 

 large and within the elongate transverse fasciolar area on either 

 side. 



Spines, pointing backwards, long and slender actinally and 

 laterally, short elsewhere, those within the subanal area pro- 

 jecting backwards in two tufts. Anal plates large near the 

 circumference. 



Fossil. Tertiary : Crimea, Corsica, Malta, Algiers, Java, Aus- 

 tralia, New Zealand. 



Recent. Guayaquil, Grulf of California, Eed Sea, Australia, 

 Philippines, Arafura Sea, Cape of Grood Hope, China, Japan, 

 Sandwich Islands. 10 to 28 f ras. 



The small forms with thick tests found in the Australian 

 Tertiaries show slight vestiges of the internal scrobicular pouches, 

 so that the genus has been modified in 1877 to receive them ; 

 there is no room for a new subgenus, such as Sarsella, which 

 would include such forms according to M. Pomel (Theses, 1883, 

 p. 36). 



