104 CALIFORNIA ACADEMY OF SCIENCES 



We have compared this species with X. agassizii from the Galapagos Islands, 

 and find it to differ in having fewer scales, a larger eye and a shorter pectoral fin. 

 X. agassizii has 58 to 61 scales; the eye is contained 3^ to 3| times in the head; the 

 pectoral reaches to beyond the origin of the anal. 



Family H^MULIDiE. 



192. Hgemulon scudderi Gill. 



The most abundant species of the genus at Panama. 



In eight half-grown specimens, five have 11 dorsal spines, three have 12 

 dorsal spines. In thirty-six young specimens, with the streaks and caudal spot 

 still conspicuous, thirty-three have 11 dorsal spines, three have 12 spines. The 

 articulated dorsal rays are 16 or 17 in number; the anal rays 7 or 8. In twelve 

 specimens from Mazatlan, ten have 12 sj^ines, two have 11. 



In young specimens, are three well-developed streaks and one rudimentary 

 one. The uppermost starts on the median line of occiput, runs to the spinous 

 dorsal, and is continued along each side of the base of the dorsal, gradually growing 

 fainter and disappearing before reaching the second dorsal. A pair begin just 

 inside the nostrils, run just above the eyes, diverging backward to a point opposite 

 the oi'igin of the dorsal, thence converging to the base of the last dorsal ray, behind 

 which the 2)air unite on upper median line of caudal peduncle, on which they reach 

 base of upper caudal rays. Another pair begin at tip of snout and extend backward 

 through eye to middle of caudal peduncle, where they become faint or entirely 

 disappear. A faint streak extends backward from upper margin of orbit to begin- 

 ning of lateral line, along the anterior part of which it may be faintly indicated. A 

 large black oval spot three-fourths the size of the eye is half on the caudal peduncle, 

 half on the base of the fin. Comparing these streaks, which disappear in adults, 

 with the permanent coloration in H. viacrostomum, we find them characterized by 

 the rudimentary condition of the streak along (or just below) the lateral line, and 

 the total absence of a streak, present in niacrostoinum, running from above eye along 

 sides just above the lateral line. 



n. scudderi differs from its Atlantic representative II. parr a: (1) In having 

 usually 11 dorsal S2:)ines instead of 12; (2) In having longer falcate pectoral fins, 

 which extend beyond the tips of the ventrals, and are nearly devoid of scales; (3) 

 In the greater compression of occiput and nape, forming a crest which may be traced 

 in adults to the interorbital space; (4) In the greater compression of the' snout, 

 which is also produced upward at tip, so that in adults the upper profile of snout and 

 head as far as occiput is concave. In H. parra, the dorsal spines are normally 12. 

 In but one specimen of imrra out of sixteen examined, have we found 11 spines, a 

 number which seems not to be recorded for the species. The pectoral fins are short 

 and rounded, not reaching tips of ventrals. They are very densely covered with 

 scales to their tips, both membranes and rays being completely invested. The 

 ventrals also are much more densely scaled than in scudderi. The occiput, nape 

 and snont are transversely broadly rounded in both young and old specimens, while 



