818 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



The greatest deptli enters the total length 2.6 times ; the length of 

 the head enters the same 3.3 times. The spines are more robust, and 

 the serrature of the preopercle more produced in the individual now de- 

 scribed than in any of those of the P. serrata in my possession. The 

 size is about the same as that of the latter species. 



Priscacara liops, s2). nov. 



A smaller fish than either of the preceding is referred to this genus, 

 although it differs in one feature, regarded as important among the 

 Fomacentridce, i. e., the preopercular border is entire. It conforms closely 

 to the P. serrata in other respects, as the form of the dorsal fin, three 

 anal spines, form of caudal fin, character of scales and lateral line? 

 edentulous jaws, and, indeed, in form to such an extent as to lead me to 

 suspect that in this genus, as in Lei^omis, etc., the serration of the pre- 

 opercle is not of much systematic value. One character by which the P. 

 lioi^s may be distinguished from P. serrata, in addition to the smooth 

 preoperculum and small size, is the constantly larger number of rays in 

 the second dorsal fin. 



Formula :— Eays : D. X— 13-14 ; C. 5—19—6 ; A. III. 10-11. Verte- 

 brae : D. 9 ; C 13. The form is characterized by the downward production 

 of the muzzle, or a descending slope of the front. One specimen does not 

 present this character, perhaps on account of distortion. The pectorals 

 originate below the first dorsal spine, and the ventrals a little behind 

 it. The spines are moderately stout, and the emargination of the dor- 

 sal fin is not deep. There are twenty-five rows of ctenoid scales trav- 

 ersed by a vertical line from the middle of the spinous dorsal, and 

 smaller scales cover the operculum and more or less of the preopercu- 

 lum. 



Measurements. 



M. 



Total lengtli 0.113 



Length of head 0.032 



Length to first dorsal spine 0.034 



Length to first dorsal soft ray 0.057 



Length to first anal spine 0.057 



Length to base of caudal ,.. 0.086 



Depth at orbit 0.030 



Depth at first dorsal spine „ 0.043 



Depth at first dorsal soft ray 0.035 



Depth of caudal i^eduncle 0.014 



Five specimens of this fish have been received. 



GENERAL OBSERVATIONS. 



The species of this locality are distributed as follows, in their respect- 

 ive genera. A corresponding list of all the species known from the 

 Green River Shale is also given : — 



