SPECIAL CHARACTERS OF GENITAL PLATES. 



1G9 



Text-figs. 190-196. — Splitting, fu.sion, etc., of genital and ocular plates, in iStrongyloccntrotu.s and Trii)iu'ustos (p. 28) . 

 190. Slrongyloccntrotus drdbachiensis (O. F. Mtillei^. York Harbor, Maine. Diam. 54 mm. R. T. J. Coll., 773. X 3. 

 Genital 3 split by one horizontal suture (compare Plate 6, fig. 4). 



190a. The same. Diam. 38 mm. R. T. J. Coll., 774. X 3. Genital 3 split by one vertical suture. 

 190b. The same. Diam. 49 mm. R. T. J. Coll., 775. X 3. Genital 3 split by three sutures. 



191. The same. Calderwood Island, Maine. Diam. 46 mm. R. T. J. Coll., 879. X 3. Genital 2 spht. 



192 



sutures. 



193 



The same. Harpswell, Maine. Diam. 43 mm. R. T. J. Coll., 776. X 3. Several genitals split by secondary 



The same. York Harbor, Maine. Diam. 46 mm. R. T. J. Coll., 711. X 4. Genitals 2, 3, and oculars HI, 

 V are split by secondary sutures; the splitting of oculars is a very rare variation (Plate 6, fig. 6). 



194. The same. Diam. 42 mm. R. T. J. Coll., 700. X 4. Genitals 1 and 2 much split up; ocular V split; extra 

 genital pores, but there is no genital pore in the madreporite (compare text-figs. 197- 199, p. 171). 



195. Thesame. Diam. 41 mm. R.T.J. Coll., 777. X 3. Genitals3, 4fused (comparePlate6, fig. 2; Plate7, fig. 7). 



196. Tripneustes esculenlus (Leske). Bermuda. Diam. 138 mm. R. T. J. Coll., 787. X 2. Genitals 5, 1 fused; 

 oculars V, IV, II insert (pp. 93, 124). 



