4 PROCEEDINGS OF THE NATIONAL MUSEUM vol.80 



The smaller specimen measures 21 mm. in the longer axis and 

 16 mm. in the shorter. The longest spines in the longer axis are 

 18 mm. in length, and the longest spines on the shorter axis measure 

 13 mm. 



The periproct is completely covered by four plates. Two of these, 

 one occupying one corner of genital 2, the whole inner edge of genital 

 3, and two-thirds of the inner edge of genital 4, and the other 

 occupying one-third of the inner edge of genital 4 and the entire 

 inner edge of genital 5, are subequal and larger than the two 

 opposite. 



The genitals are more nearly of the same size than in the other 

 specimen. Genital 2 is the largest, followed by genital 4; genital 

 3 is narrower than 2 or 4 but longer; and genital 5 is longer than 

 genital 1. The inner border of genital 3 adjoining the periproct 

 is about half as long as the inner border of the other genitals. 

 Genital 2 bears a cylindrical spine near the inner border, and genitals 

 3 and 4 have a prominent tubercle in this position but no spine; 

 genitals 1 and 5 bear neither spines nor tubercles. 



All the oculars are exsert, ocular II only slightly so, oculars I 

 and V about twice as much so as ocular II, and oculars III and TV 

 three or four times as much so as oculars I and V. Oculars I and 

 III bear each a cylindrical spine, and all the oculars bear several 

 pedicellariae. 



In color this specimen resembles the other, but the spines are 

 slightly lighter, a very few of the spines on the oral surface show- 

 ing light tips with one or two very obscure subapical dark bands. 



ECmNOMETRA MATHAEI (de Blainville) 



Four hundred and thirty-eight specimens, all but 22 of which 

 are more or less strongly flattened immature and young of various 

 sizes, and are referable to E. picta as described by A. Agassiz and 

 H. L. Clark. 



In their final account of E. picta these authors said that the more 

 the specimens on which that form is based are studied, the more 

 doubtful it seems whether it is really distinct from E. mathaei. 

 They note that in the specimens regarded as picta the test is dis- 

 tinctly flattened and is wider than usual, and the spines seem to 

 be less crowded and are somewhat more slender than in mathaei^ 

 and are much less numerous on the abactinal system. The latter is 

 distinctly larger than it is in 7natha£% its diameter sometimes nearly 

 equaling one-third of the test length. There is seldom more than 

 one secondary tubercle on each genital plate. The color. is dark 

 brown for the test and light fawn color for the spines. Agassiz 

 and Clark say that these specimens intergrade more or less com- 



