OCULAR AND GENITAL PLATES. 



101 



Table of Typical Ocular Plate Arrangement and Variation in the Cidaroida (continued). 



' Italic numerals represent percentages, Arabic numerals the number of specimens observed. 



canaliculata, and I know it only in Porocidaris milleri A. Agassiz, as figured by Mr. Agassiz 

 (1904). The genital pores are relatively huge, break through the confines of the genital plates 

 and impinge upon the interambulacra. One specimen in the seven examined has all the oculars 

 insert like the typical character of canaliculata. 



In Goniocidaris tubaria, 17 specimens, all the oculars are insert in 41 %, but there is con- 

 siderable variation. In 12% all the oculars are exsert, as in G. nutrix, in 6% ocular V, in 

 35% oculars V, I, IV, and in 6% oculars V, I, IV, III are insert. The sequence of coming in 

 is apparently V, I, IV, III, II. 



The character of the apical disc in Goniocidaris canaliculata is of especial interest as the 

 very young was studied carefully by Loven (1892) and is here figured (Plate 2, figs. 1-3). 

 Of seven adults the oculars are all broadly insert in six specimens (text-figs. 73, 74), and in the 

 seventh, oculars V, I, IV, III are insert. There is no elevated ring around the ocular pores 

 and the genital plates and pores are small, not large, in distinction from G. nutrix. The genital 

 pores, however, extend beyond the limits of the plate as in nutrix. The oculars are broadly 



