422 PROCEEDINGS OF THE NATIONAL MUSEUM vol. ii4 



The 70-mm. Tuamotu specimen was collected with rotenone on an 

 exposed reef in less than 15 feet of water near the phosphate loading 

 dock of Makatea. Amblycirrhitus himacula, Isocirrhitus sexfasciatus, 

 Cirrhitus pinnulatus, Paracirrhites arcatus, and P. hemistictus were 

 collected at the same station. 



The holotype (USNM 115750), 35 mm. in standard length, was 

 examined. The 47-mm. paratype is now in the Museum of Com- 

 parative Zoology at Harvard University (No. 37288). 



Isocirrhitus, new genus 



Diagnosis.— Uppermost and lower 5 pectoral rays unbranched; 

 dorsal soft rays 11; palatine teeth absent; upper third of free margin 

 of preopercle finely serrate, lower two-thirds smooth; suprascapular 

 margin smooth (serrate on other genera except for some species of 

 Cirrhitus, Paracirrhites and Amblycirrhitus) ; preorbital without a free 

 hmd margin and bearmg only a few scales posteriorly; interorbital 

 scaled; 4 or 5 rows of large scales on cheek; 4 rows of large scales above 

 lateral line in middle of body; depth of body 2.7 in standard length; 

 snout length about 3.7 in head length; snout not pointed, the 

 profile from interorbital to upper lip convex; a tuft of cirri from mem- 

 brane near tip of each dorsal spine; membranes of dorsal fin moder- 

 ately incised; longest dorsal spine 3.5 to 4 in body depth; first soft 

 ray of dorsal fin not produced into a filament; pectoral fins short, 

 their length about 1.4 in head length; longest unbranched pectoral 

 ray about 1.25 times longer than longest branched pectoral ray; 

 pelvic fins do not reach anus; caudal fin truncate. 



Type species. — Cirrhitoidea sexfasciata Schultz. Monotypic. 



Remarks. — Although evidently related to Cirrhitops, Amblycirrhi- 

 tus and Cirrhitichthys, Isocirrhitus is distinct from all these genera in 

 its lack of palatine teeth and the shortness of its dorsal spines. Other 

 characters, such as degree of serration of preopercle, presence or 

 absence of a free margin on preorbital, number of dorsal rays and 

 shape of snout, are variously shared among the four genera. Iso- 

 cirrhitus cannot be differentiated from Paracirrhites on the basis of 

 absence of palatine teeth and short dorsal spines; however, it is 

 separable from this genus by having 4 instead of 5 rows of scales above 

 the lateral Ime, a tuft of chri instead of a single cirrus from the mem- 

 brane near the tip of each dorsal spine, and the lower 5 (instead of 7) 

 pectoral rays unbranched. Its unbranched pectoral rays are not as 

 long relative to the branched rays as those of Cirrhitops, Ambly- 

 cirrhitus and Cirrhitichthys but longer than Paracirrhites. 



