134 



ROBERT TRACY JACKSON ON ECHINI. 



1 



Text-fios. 140-149. — Principal aberrant variants in ocular plate arrangement of Strongylocenlrolus drobachiensis 

 (O. F. Muller) (see pp. 93, 94, 164). 



140. Calderwood Island, Maine. , Diam. 32 mm. R. T. J. Coll., 87S. X 3. Ocular IV only insert, a rare variant. 



141. Dumpling Lslands, Maine. Diam. 64 mm. R. T. J. Coll., 849. X 3. Oculars I, II insert; compare Gymncchi- 

 nus, text-figs. 177-179, p. 165. 



142. Dumpling Islands, Maine. Diam. 60 mm. R. T. J. Coll., 850. X 3. Oculars V, IV insert, a left-handed 

 etiuivalent of text-fig. 141. Madreporic pores in genitals 2 and 1 (p. 172). 



143. Dumpling Islands, Maine. Diam. 42 mm. R. T. J. Coll., 867. X 3. Oculars I, V, IV insert, but ocular IV 

 and genital 4 are fused (p. 168). 



144. Dumpling Islands, Maine. Diam. 47 mm. R. T. J. Coll., 852. X 3. Oculars I, IV insert, an incomplete I, V, 

 IV, due to the exclu.sion of V by the fusion of genitals 4, 5 (p. 167). 



145. Dumpling Islands, Maine. Diam. 56 mm. R. T. J. Coll., 851. X 3. Oculars I, V, II insert, the commonest 

 aberrant variant, a right-handed equivalent of the normal progressive variant, I, V, IV insert (pp. 93, 141). 



