234:0 Bulletin ^7, United States Natioiial Museum. 



867. ARBACIOSA, Jordan & Evermann. 



Arhaciosa, Jordan & Evermann, Proc. Cal. Ac. Sci. 1890, 290 (humeralw.) 



This genus differs from Gobiesox chiefly in the character of the incisor 

 teeth of the lower jaw; these are strongly serrate, or tricuspid, making a 

 ragged cutting edge. Size small; dorsal and anal comparatively short; 

 head not very broad, the jaws contracted; vertebra (in Arhaciosa zebra) 

 28. Some species provisionally referred to the section Sicyascn of Gobiesox 

 may prove to belong to Arhaciosa; small species, living in rock pools, 

 among the sea urchins, by whose spines they are protected. This relation 

 of Arhaciosa zehra with the Echiuoid Arbacia steUata is esjiecially constant. 

 (Arbacia, a sea urchin.) 



a. Anal fin long, about 10 rays; dorsal rays 11 ; teeth above in 1 series ; color olivaceous. 



KHESSODON, 2682. 



aa. Anal fln of 5 to 7 r.ays. 



6. Dorsal fin of 8 or 9 rays; teeth in single series; color brownish, with red bars 



and a large black humeral spot. humeralis, 2683. 



hb. Dorsal fln of 7 rays ; color greenish, with pale spots and numerous pale cross 



bands; no red; body slender. rupestrls, 2684. 



bbb. Dorsal flu of rays; color chiefly red. 



c. General color pinkish olivaceous, with some bright red; back with 5 

 reddish-brown or blackish bars. Upper teeth in more than 1 series. 

 Body comparatively slender, the depth nearly 8 in length. 



ZEBRA, 2685. 



cc. General color bright rosj- red, black, with 1 to 3 faint dark bars. Upper 



teeth nearly uniserial. Body comparatively stout, the depth 5J in 



length. KOS, 2686. 



2682. ARBACIOSA RHESSODO' (Rosa Smith). 



Head 3i; depth 6i. D. 11; A. 10; eye 4^ in head, f in interorbital 

 space ; ventral disk 1^ in head ; pectoral 2 ; caudal 2^. Form much as in 

 Gobiesox mwandricus ; snout bluntly and evenly decurved; the greatest 

 height of the body across the pectoral fins; head broader than body but 

 less deep; maxillary extending to l)elow the eye; incisors of lower jaw 

 not much declined, each of them tricuspid, the central cusp longest; teeth 

 of tipper jaw conical, in an irregular series of 7 to 9; teeth in each jaw 

 in single series; opercular spine sharp; distance from vent to caudal 2f 

 in length ol" body ; dorsal a little longer than the anal, having its origin 

 in advance of the anal and terminating opposite it; caudal rounded. 

 Color dark olivaceous, tisually with 3 broad yellowish cross bands above, 

 the first across interorbital space and cheek, the second very Avide, across 

 back and front of dorsal fin, the third below middle of dorsal, some or 

 all of these sometimes wanting ; a dark bar at base of caudal ; belly yel- 

 lowish. Length 2| inches. San Diego to the northern part of the Gulf 

 of California; locally abundant in rock pools. {pi)66G0, to make ragged; 

 oSovi, tooth.) 



Oobiesox rhessodon, Rosa Smith, Proc. U. S. Nat. Mus. 1881, 140, San Diego, California; 

 Jordan & Gilbert, Synopsis, 749, 1883; Rosa Smith, Proc. U. S. Nat. Mus. 1883, 235. 



