190 PANAMIC DEEP SEA ECHINI. 



On the actinal side the interatnbulacral plates are very large, expanding into 

 irregularly shaped plates forming the anterior and posterior lateral ambu- 

 lacra. As in Paleopneustes crista! 'us (PI. 95) the primordial plates of the lateral 

 posterior ambulacra are excluded from the actinal system (PL 88, fig. 4) 

 though in young stages of both genera they abut on the actinal system 

 the whole width of the primordial plate. 1 In Paleopneustes hystrix a thin, 

 narrow prolongation of these plates extends to the actinal system (PI. 97, 

 fig. l), as in Linopneustes longispinus (PI. 92). 



Judging from the fragments, the largest specimens must have been at 

 least 50 mm. in height and over 100 mm. in length, with a greatest 

 width across the anterior half of the posterior interambulacra of from 80 

 to 90 mm. When alive the color of the test was yellowish brown with 

 darker reddish brown primary and secondary tubercles. Its coloring was 

 much that of Linopneustes Murrayi. 



Station 3306, east of Cocos Island in 1007 fathoms. Lat. 5° 30' N. ; 

 Long. 8G J 45' W. Bott. temp. 37 . Y. glob. ooze. 



BRISSINA Gray. 



Bkissopsis Agass. 



Brissopsis colurnbaris A. Ag. 



Brissopsia columbaria A. Ag., Bull. M. C. Z. 1898, XXXII, No. 5, p. 82. 



Pis. 100. figs. G, 7 ; 102, figs. 5-9 ; 103, figs. U -'. 



Brissojms columbaris adds another representative species to those found 

 on the two sides of the Isthmus. The changes due to growth are similar to 

 those of the Atlantic species, to which I have called attention in the Re- 

 vision of the Echini. The petals, flush with the test in young stages, grad- 

 ually become more sunken (Pis. 100, figs. 0, 7 ; 102, fig. J; 103, figs. J, .'). 

 The regular elliptical outline of the fasciole becomes indented in older 

 specimens. The subanal fasciole sends out no brandies in the younger 

 stages, which are globular and truncated at the extremity, while the out- 

 line becomes indented and covered with a closer tuberculatum in older 

 specimens. 



1 « Blake" Echini, PI. XXI, figs. 11, 13. 



