TENTATIVE ARRANGEMENT OF TJIE GENERA OF MYCTOPIIID^E. 



I. Body oblong, compressed. Teeth in Jaws in villiforra bands. 

 A. Peotiirals present. 



1. Dorsal and anal fins touching (or nearly so), the same vertical, or overlapping. 

 a. Lateral line not at all, or but slightly, enlarged, i^rale.s cycloid, smootli. 



i. Xo tuminims glnniU on head or tail. ( Lutnhiniut xcalen somclimrs prnifnl mi tnil, <ilioi-c or 

 hfhiw.) 

 X. Head short, with limb of preoperculnm nearly vertical ; snout more or less blunt 

 and declivous. Trecaudal photophores 2. 

 Dorsal entirely in front of anal, and scarcely, or not at nil. overlapping. Superanal 



photopliores in two groups Myctophgm 



Dorsal overlapping anal. Superanals in one or two groups Bexthosema. 



XX. Head long, limb of preoperculnm oblinne, snout conical and snake-like. Precaudal 

 photophores 4 or 2 + 1, 

 Dorsal about equal to or shorter th.an anal, and not overlapping. 



No orbital spines LAMr.A,NYCTUS 



Orbital spines Ckratoscopeli-s 



Dorsal much longer than anal, and overlapping it. 



Pectorals placed normally Notoscopelus 



Pectorals pi aced very low C atablemella 



ii. Luminoiia gland.t on tail, int none on head. 



X. Dorsal and anal nearly equal, not touching same vertical. 



Head somewhat conical, with limb of preopercnluni slightly oblique. 



Saddle-like gland on tail, above and below Lampadena 



iii. iMrqc luminous t/hinds on head, iiut none, on tail. 

 X. .Superanal photophores in two groups. 

 Precaudal photophores 4. 



One large, irregular gland occupying entire front of head yETHOPRiiRA 



Four Itiuiinous glands on head, one in front of e.ich eye .and (me on each 



infraorbital Collettia 



Precaudal photophores none. 



A gland in front of each eye below the nostril. 



Photophor.-s and cephalic glands all divided into halves by horizontal septa 

 of black pigment Diaphus 



b. Lateral line obsolescent. 



i. Xo luminous ylands. riiotophorcs much as in tiipical genus. 

 X. Head long, with oblique preopercnlar limb. 



Dorsal overlapping anal, the latter much the longer. Pectoral inserted high up. 

 Precaudal photophore 1. Apparently no photophores on head.TARLEToNBEAXiA 



c. Lateral line with scales much enlarged ; scales hard, persistent. 



i. Luminous glands or scales on top of caudal peduncle; none on liead. 

 X. Scales cycloid. Anal passing behind soft dorsal. 



Body elongate, fusiform; head short, with projecting snout. 



Anal much longer than dorsal, but not overlapping. Caudal peduncle slender, 

 elongate. 

 One posterolateral photophore over break in superanal series. 



Rhinoscopei.vs 

 Body ovate, compressed; head short, profile declivous; snout not projecting. 



Anal somewhat longer than dorsal and overlapping it slightly. Caudal peduncle 

 short and stout. 

 No posterolateral photophore. Superanals in unbroken series. .Electrona 

 xs. Scales ctenoid. Anal terminating below soft dorsal. 



Body elevated, somewhat compressed. Caudal peduncle rather r lender. 



Anal longer than dorsal, but scarcely overlapping Da.s yscopelus 



2. Dorsal an<l anal short, similar, far apart. 



a. Scales large, very deciduous, covered with minute spines. 



i. Xo luminous glands on head or tail. 



X. Scales along belly with luminous centers. Photophor.-s far from normal. 

 Head conical; rictus short. 



Dorsal and anal equal, the latter place.l with its cent..r umler .soft dorsal. 



Xkoscopklus 



b. Scales (if present) very deciduous. 



i. Month very large ; maxillary mu<-h dilated at tip ^<■oPEI.EX(;Y3 



B. Pectorals rudimentary. 



1. Dorsal and anal overlapping considerably. 



a. Luminous glands on tail, above and helow. Fhotophores minxUe, inrgularlg placed. 



i Head Ion.', with oblique preopercnlar limb; snout coni.al; mouth terminal. Iion- 

 ' . , ...Naxxobraciium 

 zontal 



IL Body elongate, cylindrical. Teeth in lower jaw in several scries SCOPELosaURUS 



