148 



I'ALU'UKNIA AtADEMV Ul' SCIENCES 



A/tasiiremenls in Hundredths of Length without Caudal. 



Lenjjtli in mm 



Head (to edjife of membrane). 



Snout 



Interorbital width 



I ")iamcter of iris 



Depth opposite first anal spine 



Longest dorsal ray 



Longest anal ray 



Longest pectoral ray 



Longest ventral ray 



276. Parapsettus panamensis Steindachner. 



Not rare in the Panama market, where numerous specimens were obtained. 



In addition to the short grachiated dorsal spines, this genus differs from 

 Chfpfodipierus in having no transverse fold behind the upper lip, which is therefore 

 technically as well as actually non-protractile. The shoulder-girdle agrees with 

 Chcetodipierus. The alisphenoids are much more developed, meeting each other 

 raesially, and closing the cranial cavity in front. The interorbital septum contains a 

 well-developed osseous lamina, which comes in contact posteriorly with the strong, 

 compressed, vertical limb of the basisphenoid. Tlie latter fails to meet the para- 

 sphenoid below. 



Family CH/ETODONTIDyE. 

 277. Chsetodon nigrirostris (GUI). 



P1.ATB XXIV, Fk;. 47. 



Two adults of this apparently rare species were taken by the use of dyna- 

 mite near one of the rocky islands in Panama Bay. 



In addition to the distinctive color-markings, this species has the scales on the 

 cheeks enlarged, the exposed surfaces much higher than wide, arranged in four 

 horizontal more or less wavy series, but not in quincunx order. The preopercle is 

 strongly striated. 



The head and the lower half of body are silvery, more or less washed with 

 light yellow, each scale having often a brownish spot at base, these forming three 

 faint lengthwise stripes along the scale-rows. The base of the anal, and the upper 

 half of the trunk are light brownish purple. A jet-black bar encircles upper part of 

 snout, but does not include the upper lip, nor the region behind the vertical from the 



