SPATAGODESMA DIOMED^. 201 



The existence of simple pores in the anterior zones of Agassizia has usu- 

 ally been looked upon as an abortion of the second pore of the pair, and 

 not as a character indicating its Ananchytid relations. 



The actinostome is near the labium. The actinal system is pentagonal 

 with rounded corners; the plates covering it are barely indicated ; they are 

 large and few in number, much as in Agassizia (PI. 107, fig. ,"). There is a 

 single spheridium in the actinal plate of each ambulacral area. Seen from 

 the actinal side (PI. 107, fig. /) the ambulacra are bare ; the interainbulacral 

 areas alone are covered by large primaries. Seen in profile (PL 107, fig. 8) 

 the lateral ambulacra continue bare along the sides of the test and as far as 

 the apical system; within the peripetalous fasciole (PI. 107, fig. 2) the inter- 

 ambulacra alone carry primary tubercles. 



The spines of the abactinal side trend towards the anterior extremity ; 

 those of the ambitus towards the posterior part of the test. On the ster- 

 num the primary radioles of the test are fluted, spatulate, rounded at the 

 extremity, covered with sharp lateral spines, (PI. 107, figs. 6', 9); those of 

 the fascioles are short, straight, carinate, slightly expanded at the extremity 

 (PI. 107, fig. 10). 



5.3 mm. 5.3 mm. 



Fig. 288. S. Diomed.e. Fig. 289. Spatagodbsma Diomep.e. 



The anal system is slightly pointed, covered with irregular elliptical 

 plates, largest at the abactinal edge and decreasing in size towards the anal 

 opening, which is close to the actinal edge of the anal system (PI. 106 

 fig. 3). 



The general outline of the test as seen from the actinal side (PI. 107, 

 fig. 1) is elliptical, slightly truncated anteriorly, somewhat indented ; the 

 actinal side is arched both laterally and longitudinally (PI. 107, figs. 3-5). 



