.EIS; SYSTEMATICS AND ZOOGEOGRAPHY OF THK PORCUPINEFISHES 



Figure 21. — Developmental stages of Diodon holocanthus 

 eggs: (A) blastopore closure, (B) middle stage, and (C) late 

 stage. Egg diameter ca. 1.75 mm. 



Late stage (tail bud completion to first eye pig- 

 mentation and melanophores on body. Figure 

 21 ). The oil droplets are on the ventral surface 

 of the yolk sac. The head becomes very broad 

 and enclosed by an inflated vesicular dermal 

 sac which eventually expands to enclose the 

 entire body by the end of this stage. The pec- 

 toral fins are well-formed and are occasionally 

 moved by the embryo. An odd hooklike struc- 

 ture which seems to be the incipient pectoral 

 girdle can be seen in live material in the vicin- 

 ity of the base. The gut forms a long, straight 

 tube. The eyes develop their first pigment dur- 



ing this stage, and a few melanophores appear 

 on the head and dorsal surfaces. At about this 

 time red chromatophores appear, scattered 

 throughout the dermal sac and on the fin buds 

 and folds. 

 Final stage (acquisition of full eye pigmentation 

 through hatching). The oil droplets are no 

 longer visible, being enclosed with the yolk 

 sac within the abdomen. The mouth apparent- 

 ly becomes functional now, and the exhalant 

 gill openings are visible. The eyes are com- 

 pletely, if lightly, pigmented. Body 

 melanophores have spread over most of the 



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