72 



U. S. p. R. R. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



about three inches and a quarter in total length, the head constituting also the third of it, the 

 caudal fin excluded. The occipital region is depressed, and the interocular region, which is 

 broader tliaii in the preceding species, instead of being convex, is groove-like. The rostral 

 distance is gently sloping towards the extremity of the snout, exhibiting two stout and con- 

 spicuous nasal spines, behind which is a depression for a tubular posterior nostril, the anterior 

 nostril being, as usual, on the side of the snout nearer the orbit tlian the extremity of the ros- 

 trum. Tlie posterior extremity of the maxillary extending to a vertical line passing rather 

 posterior to the middle of the pupil. The eye is large, sub-circular, placed towards the upper 

 surface of the head ; its horizontal diameter is contained four times in the lengtli of the sides of 

 the head, not quite once in advance of the anterior rim of the orbit. A short and flattened 

 tricuspid process may be observed upon the convexity of the preopercle, two of the spines 

 pointing upwards, the third downwards. Upon the inferior branch of the same bone there are 

 two minute spines, whilst a third one, directed forwards, is inserted upon the interopercle. 



The general disposition and structure of the fins is the same as in the preceding species ; the 

 origin of the anal, however, is opposite the third ray of the second dorsal, and not as deep as 

 the latter is high, and the insertion of the ventrals situated upon a vertical line intersecting the 

 middle of the base of the pectorals. 



Br. V: V; D IX, 15 ; A 10 ; C 3, 1, 5, 4, 1, 2 ; V I, 3 ; P 17. 



A membranous flap may be seen upon the posterior superior rim of the orbit. The occipital 

 region is provided with small spines and tubercles, symmetrically disposed, whilst the entire 

 surface is spread over with small scales, similar to those of the dorsal region, with the only 

 dift'erence that the ciliated edge is less conspicuous. These scales extend over the temporal 

 region, opercular apparatus, and between the orbits. The dorsal band has the same disposition 

 as in the preceding species, but it is broader, though composed of a smaller number of scales ; the 

 latter are more apart and their edge more strongly ciliated, or rather spinous. The lateral line 

 is very conspicuous, and its curve depressed upon the middle of the flanks. 



The ground color is olivaceous, darker above than beneath. A series of four black, saddle- 

 like spots, may be observed along the back— the first one across the anterior dorsaj, the second 

 and tliird over the second dorsal, and the fourth upon the peduncle of the tail, between the two 

 fins. The lower half of the sides, below the lateral line, is ocellated with dull white or yellow. 

 The inferior surffxce is unicolor. The fins are unicolor, of the general hue of the region to which 

 they respectively belong. 



Beferences to the figures. — Plate XXII h, fig. 5, represents Arledius notospilotus, from San 

 Francisco, California, and size of life. Fig. 6, a dorsal scale-like shield, magnified. 



List of specimens. 



329 

 307 

 613 



o o 



Yg- 

 Adt. 

 Yg- 



Locality. 



Tonuiles bay. C;il 



San Francisco, Cal 



Ft Townseiid, Puget's S'd 



185C.. 

 1857.. 



Whence obtained. 



E. Samuels. 

 Dr. Ayrcs.. 



July, 1856 Capt. Murdcn , 



36 



Collected liy — 



Alcoholic. I E. Samuels 



do Dr Ayres 



do ' Capt. Murden. 



