134 



ROBERT TRACY JACKSON ON ECHINI. 

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TEXT-FIGS. 140-149. Principal aberrant variants in ocular plate arrangement of Strong yloccnlrolus drobachiensis 

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



140. Calderwood Island, Maine. Diam. 32 mm. R. T. J. Coll., 878. X 3. Ocular IV only insert, a rare variant. 



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

 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 

 equivalent 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 exclusion 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). 



