98 COXTRIBUTIOXS TO T^TORTII AMERICAN ICHTHYOLOGY IV. 



and below the caudiil peduncle. Anal fin comparatively short, and rap- 

 idly increasing in heij^lit for the firsthalf of its length ; it has 12-20* rays. 

 Ventrals rounded, and each has 1 simple and 8 branched rays. Pec- 

 toral fins with, a sharp spine, of different forms in the different species. 

 Yent at some distance in advance of the anal. Lateral liue complete. 

 In or above the axil of the pectoral fins is an orifice, which is the open- 

 ing- of the duct of a poison gland. "From it may freqnently be drawu a 

 solid gelatinous style ending in a tripod, each limb of which is dichoto- 

 mously divided into short branches of regular length." (Cope.) Size 

 small. Fresh waters of the United States, (vwroc, back; oopa,tiiil', 

 "means tail over the back", Rajinesque.) 



* Premaxillary band of teeth without lateral backward processes. (Sclillbeodc8\ 

 Bleeker.) 

 t Pectoral spine entire or grooved behind; adipose fin high and continuous with 

 the caudal. 

 a. Pectoral spine about half the length of the head. 



§4. N. g-ya'iatias (Mitchill) Raf. 



Nearly uniform yellowish brown, sometimes blackish, without trans- 

 verse blotches ; a narrow dark lateral streak and one or more dorsal 

 ones. Body comparatively short and thick. Head large, its width 3^- 

 4i in length of body ; depth i-5^ ; head 3^-1. Spines stout and rather 

 long ; that of the pectoral fin straight, grooved behind, 2|- in the distance 

 from snout to dorsal fin. Dorsal higher than long, inserted nearer anal 

 than snout. Anal 13. Jaws nearly equal, numeral process short. L. 

 5 inches. New York, entire Mississippi Valley, and Upper Lake region ; 

 rather common. 



(Sil'irm (jurinus Mitchill, Amer. Month. Mag. 1818, 322; Jordan, Bull. U. S. Nat. 

 Mus. X, 102: Xoiurun 8iaUs Jordan, Bull. U. S. Na.t. Mus. x, 102, 1877.) 



aa. Pectoral spine less than one-third the length of the head. 



85. TV. IcptacaEBtSi^ls Jordan. 



Color yellowish, somewhat mottled. Body slender. Head small and 

 narrow, longer than broad. Eye small. Upper jaw much projecting. 

 Spines very short and slender ; that of the dorsal not one-third the 

 height of the fin ; all less than one-third the length of the head ; that 

 of the pectoral retrorsely serrate on the outer edge, entire within. Head 

 4|- in body; its width oA ; depth 5 J ; distance to dorsal 24 ; pectoral spine 



* Throughout the account of this iamily the rudimentary rays at the front of the 

 anal are included in the enumeration. 



+ Bleeker, Ichthyo]ogi;T3 Archipelagi Indict Prodromus, i, Siluri, 258: type Silurus 

 gyrinus Mitch. {Schilbe, another genus of SUurldai ; eido^; like.) 



