NATURAL SCIENCES OF PHILADELPHIA. 133 



Color black, darkest on the skies ; head speckled with paler. 

 Total length .072; to caudal fin, .059; to dorsal fin, .028; to 

 dorsal shield, .025 ; to line of anterior humeral tuberosity', .008 ; 

 to orbit, .003. 



From Nauta. The dorsal fin is apparently more posterior than 

 in B. gronomi, and there are fewer anal rays than in B. aleiii'opsis. 



Dysiclithys coracoideus, gen. et sp. nov. 



Char. Gen. In general similar to Bunocephalus, but there are 

 no mandibular nor mental barbels. The head is depressed, but 

 deeper than the narrow tail. 



Char: Specif. Radial formula, D. 5 ; A. T ; C. 10 ; Y. 6 ; P. I. 

 4. Dorsal fin bound to the back behind by its membrane, the 

 base of its first ray a little nearer the end of the muzzle than the 

 basis of the caudal fin. The head and neck shield is diamond- 

 shaped, with truncate angles, and the humeral angles mark the 

 middle of its length instead of an anterior point, as in Bunoce- 

 pha.lus nelas. The anterior humeral tuberosity marks one-third 

 the length from the end of the muzzle to the second dorsal ray, 

 measured axially. The shield is peculiar for its strong ridges 

 and scalloped borders. A bigh heel, with three prominences, 

 divides it behind, while the scutum supports another. The poste- 

 rior border presents two angles, and there is a ridge across behind 

 the orbits. A ridge from each orbit meets its fellow, forming a V 

 at the occiput, and a ridge from the humeral process meets its 

 fellow behind this point. The postcoracoids are longer than in 

 B. melas., their length equalling the width between them. The 

 pectoral spines extend bej^ond the base of the dentrals. The 

 maxillary barbels extend to the base of the pectoral spines. The 

 tail is quadrangular with a line of evantlets along the lateral 

 angle. Belly, tail, and fins, black ; throat and belly white speckled. 

 Shield brown, with some paler specks. Total length, .055 ; do. to 

 caudal fin, .046; do. to dorsal, .021 ; do. to dorsal scutum, .018; 

 do. to humeral tuberosity, .010 ; do. to orbit, .003. 



Several specimens from Nauta. 



Zathorax nauticus, sp. nov. 



Coracoid portion of the scapular arch only ossified so as to 

 occupy the derm. Postcoracoid narrow, not excavated. A dis- 

 tinct adipose fin. Prefrontal bone acutely pectinate on its upper 

 face. Head (to end of casque) one-third length to middle of caudal 



