ECHINOCREPIS SETIGERA. 



145 



loses itself on the abactinal side toward the ambitus. 1 The short size of the 

 actinal pouch is well seen in PI. 69, figs. /, .'. on comparing it with the 

 long fossa of Pourtalesia Tanneri (PI. 57, fig. #), which extends the greater 

 part of the length of the odd ambulacrum. 



The primary tubercles on the abactinal part of the test are but few in 

 number, only from one to three on each plate, Fig. 210. and even these 

 are sometimes wanting. Many of the plates on both surfaces only carry 

 one tubercle, and most of the anterior ambulacral plates are bare, or only 

 thickly covered with diminutive miliaries (PI. 67, fig. 4), as are all the 



III b. U2 mm. 



Fig. 210. Echinocrepis setigera. 



92 mm. 

 Fig. 211. E. SETIGERA. 



plates of the test (Pis. 67; 68, fig. 5). As the coronal plates approach the 

 ambitus, they carry a greater number of primaries, five to seven, usually 

 placed near the lower part of the plate, Pig. 211. At the ambitus the 

 narrowing of the plates is also accompanied by a more crowded and smaller 

 tuberculation which extends to all the plates of the actinal side (PI. 67, 

 figs. IS). 



The plates of the anterior interambulacra on the actinal side are crowded 

 with small primaries which extend to the ambitus (PL 67, fig. /). The 

 great variation in the distribution and size of the primary tubercles is 

 in marked contrast with the uniform tuberculation which extends over the 

 test of E. cuneata? In the fragment of another specimen the arrangement 

 of the primary tubercles above the ambitus was most irregular, the plates 

 carrying from one to five tubercles or being bare. Near the apical system 

 the primary tubercles were closely packed ; this is also well seen in the odd 

 anterior ambulacrum, Fiij. 210. On the sides of the test the secondaries 

 run in slanting lines (PI. 67, fig. S). 



1 "Challenger" Echinoidea, PI. XXXV», figs. 9, 10, 12. 



2 "Challenger" Echinoidea, PI. XXXV", figs. 9-12. 



10 



