Distinguishing features. — A single species of Scor- 

 paenodes. S. xyris, is known from the eastern Pacific. 

 Comparison of S. xyris larvae with those of congeners is 

 not possible since we have only S. xyris larvae in our col- 

 lections. 



The smallest larvae of S. xyris in our collections are 1.8 

 mm in length. These specimens have already exhausted 

 their yolk supply, so it is likely that newly hatched lar- 

 vae of S. xyris are slightly smaller than 1.8 mm. Larvae 

 reach a maximum length of 14.0 mm and transfor- 

 mation into benthic juveniles occurs within a size range 

 of 11.0 to 14.0 mm. 



Scorpaenodes xyris larvae are deep-bodied; body 

 depth increases gradually during the larval period. It 

 averages 28% of body length before notochord flexion, 



Table 31. Measurements {mn) of larvae of Scorpaenodes xyris . {Specimens between dashed 

 lines are undergoing notochord flexion.) 



*Transfonning specimen. 

 **6enthic juvenile. 



33% during flexion, and 39% after the completion of flex- 

 ion (Table 31). In the slightly more elongate trans- 

 forming specimens and newly transformed juveniles, 

 body depth is 36% of body length. 



The gut is compact in small larvae of S. xyris. Snout- 

 anus distance undergoes a relative increase throughout 

 the larval period. It averages 46% of body length prior to 

 notochord flexion, 52% during flexion, 61% in post- 

 flexion larvae, and 64% in transforming specimens. 



The large spiny head is a prominent feature of S. xyris 

 larvae. Head length increases from a mean of 30% of 

 body length in preflexion larvae to 34% in larvae under- 

 going notochord flexion, to 38% in postflexion larvae and 

 transforming specimens. The eyes are relatively small; 

 eye diameter averages 30% of the head length for the en- 

 tire larval period with no obvious trend of relative in- 

 crease or decrease. The snout length is relatively short in 

 newly hatched larvae (25% of head length), increases to a 

 relative maximum length during notochord flexion 

 (average of 36% of head length), and then gradually 

 decreases during the remainder of the larval period to 

 25% of head length. 



The smallest larvae (1.8 mm) in our collection have 

 pectoral fins with the base and blade well differentiated. 

 The fins enlarge rapidly and are prominent fan-shaped 

 structures in larvae larger than 3.0 mm. Fin length 

 averages 22% of body length prior to notochord flexion, 

 34% during flexion, and 39% during the remainder of the 

 larval period. They shorten during transformation (aver- 

 age of 36%) and are about 35% in newly transformed 

 juveniles. The base of the pectoral fin is wide as in other 

 scorpaenine genera. It averages 18% of the body length 

 for the entire larval period. Ossification of the rays begins 

 in 4-mm larvae (Table 32). The full complement of 16 to 

 19 rays is present in larvae longer than 4.7 mm. 



The anlage of the caudal fin is present in 2-mm lar- 

 vae. The hypurals begin to ossify in 5-mm larvae and the 

 full complements of 3 superior and 2 inferior elements are 

 ossified in 8-mm larvae. The principal caudal rays begin 

 to ossify in 4-mm larvae and the full complement of 8 



Table 32. Meristics from cleared and stained larvae of Scorpaenodes xyris . 



53 



