Jordan and Evermann. Fishes of North America. 553 



i. Head long, with oblique preopercular limb; snout conical; mouth terminal, hori- 

 zontal. NANNOBRACHIUM. 

 II. Body elongate, cylindrical. Tooth in lower jaw in several series. SCOPELOSAURUS. 



Besides the species mentioned below, very many others are known from 

 the open Atlantic and Pacific, any of which are likely to be found off our 

 coasts. Descriptions of most of the known species are given in the papers 

 above mentioned of Liitken and of Goode & Bean. 



a. Dorsal fin not ending much, if any, before front of anal fin. 



6. Caudal photophores 4 or 3, never 2; dorsal fin not much, if any, shorter than anal; body 

 deep or slender, not much contracted behind, the caudal peduncle robust; edge of 

 preopercle more or less oblique; pectorals long or short, placed rather low. 

 c. Dorsal fin very long, much longer than anal and overlapping the latter; pectorals 

 small, narrow, placed low; head long and low, with small eye. 



MACROSTOMA, 257. 

 cc. Dorsal fin not much longer than anal. 



d. Head without large luminous glands; pectorals long or short,with narrow base. 

 e. Pectoral fins long, reaching past ventrals; luminous glands on caudal 



peduncle above or below, occasionally present. 

 /. Orbit with a small antrorse spine or horn above front of each eye. 



CERATOSCOPELUS, 258. 



ff. Orbit without antrorse spine above. LAMPANYCTUS, 259. 



ee. Pectoral fin small or minute, not much longer than eye; usually a lumi- 

 nous blotch on caudal peduncle above or below, or both. 

 g. Scales in lateral line not larger than the others. LAMPADENA, 260_ 

 gg. Scales in lateral line notably larger than the others. 



NANNOBRACHIUM, 261. 



dd. Head with large luminous glands before or below eye; pectoral fins short and 

 broad, placed low; eye very large; snout short and convex; scales in lat- 

 eral line usually more or less enlarged, the pores lujninous. 

 7. Photophores and luminous glands most of them divided into halves by cross 

 partitions of black pigment giving the form of the letter 0; a luminous 

 gland in front of each eye below nostril. DIAPHUS, 262. 



///. Photophores simple, without septa. 



i. Luminous blotches before and below eye separate. 



^ETHOPRORA, 263. 



it. Luminous blotches be fore and below eye coalescent in one large blotch 

 occupying whole front of head. COLLETTIA, 264. 



6l>. Caudal photophores 2, never 3 or 4; dorsal fin notably shorter than anal, its rays 9 to 

 14; anal rays 16 to 20; body deep anteriorly, the caudal peduncle slender; edge of 

 preopercle nearly vertical; pectorals long, placed high; no luminous glands on 

 head; eye large. 

 j. Lateral line well developed. 

 I: Scales cycloid. 



I. Maxillary scarcely enlarged at tip; last rays of dorsal not behind first of 



anal. 



m. Snout prominent, projecting beyond tip of lower jaw; scales of lateral 



line more or less enlarged; caudal peduncle very slender; usually 



a luminous gland on its upper surface. RHINOSCOPELUS, 265. 



mm. Snout little prominent, scarcely projecting beyond tip of lower jaw; 



scales of lateral line usually not enlarged; no luminous glands 



on upper edge of tail; moderately elongate. MYCTOPHUM, 266. 



II. Maxillary abruptly dilated at tip; last ray of dorsal behind first of anal; 



form moderately elongate (not broad-ovate as in the European group 



Electrona). BENTHOSEMA, 267. 



kk. Scales ctenoid, firm; tail with a luminous gland above. DASYSCOPELUS, 268. 



jj. Lateral line obsolete; no glands on tail; scales crenulate. TARLETONBEANIA, 269 



