34 DEEP-SEA FISHES OF THE ATLANTIC BASIN. 



Order MALACOPTERYGII. 



Symplcctlc present. No iuterdavick's. A luesocoracoid arch. Anterior vertt'bra' sini- 

 jile. No W'ebbcrian ossicles. Pharyngeal bones simple above and below, the lower not 

 lalcilorni. Gills lour, a slit behind the fourth. (Gill.) 



KEY TO THE DEEP-SEA FAMILIES. 



McKocoraroid well dcreloped ((« a hridgc hcttreen the lii/jH-r- and hi/jw-coracoid. (Gill.) 



I. No linrbcl anil no jihotophores. Muxillaries form margin of njipcr jaw. 



A. AUipose fin absent. Body scaly. 



1. Dorsal fin similar to and opposite anal. No air-bladder Alkpockphalid-K 



2. 1 )or.sal lin similar to and opposite anal. Air-bladder present PTKROTHElssiDyE 



15. Adii>ose tin present. 



1. Gill membranes separate and free from isthnnis. Stomach (-eeal. 



a. Brancliiostegals, 6 or more Argextimd.e 



b. Braiubiostegals, 4 or less JIkrosto.mid.e 



2. Gill membranes joined, forming broad liridge across isthmns; gill cavity closed behind. 



a. Ventrals ojiposite posterior end of dorsal Bathylagid.e 



Mesocoracoid wanting or atrophied. (Gill.) 

 I. Post-temporal connected with back of cranium near sides. No pliotophores or barbel. 



A. Adipose fin typically present. ' Body not very elongate. Anal distinct. 



1. Scales present, persistent (in all Atlantic forms). Teeth cardiform or villiform. 

 a. No photophores. Teetli cardiform, usually hinged. 



1. Maxillary narrow or rudimentary. Hypocoracolds not divergent Synodoxtid.e 



II. Maxillary dilated behind. 



* Pectorals noraial. Hypocoracolds divergent Aui.opid.e 



* • Pectorals subliumeral BenthosaukiD-E 



* * * Pectoral rays elongate, in two groups Batiiyptekoid.-e 



B. Adijiose tin absent. 



1. Scales large, thin, and deciduous. Teeth villiform, in bands. 



a. No photophores on the scales, but a large, luminous, cephalic plate. 

 I. Maxillary dilated behind. 



* Pectorals and ventrals well developed, approximate iPXOPin.E 



2. Body scaleless. 



a. Teeth granular, in bands. Pectorals normal. 



I. Ventrals jiresent. Opercular apparatus incomplete Rondeletiii'.e 



II. Ventrals al)sent. Opercular apjiaratus complete; a cousiiicuous lateral furrow. 



C'KTO.MIMII).E 



II. Post-temporal impinging uj>on occijiut. 



* Vertebra' and neural spines normal. 



A. Photophores present, barbel absent. 



1. Psendobrauchia^ present. 



a. Premaxillaries forming margin of upper jaw. Body scaly MvcTOPHiDiE 



b. Maxillary and intermaxillary together forming margin of upper jaw. Body naked. Oper- 



cular apparatus incomplete Maurolicid^ 



2. Pseudohrau(!hia' absent. Mouth large, with strong canines. Scales decidu<ms. 



a. Dorsal In front of ventrals. Anal short. Canines immense. Operculum incomplete. 



(^HAULIODOXTII).E 



b. I Jorsal behind ventrals. Anal long. Operculum well developed GONOSTOJiiDji 



B. Photoplmres and bjirliel liotli jirescnt. 



1. Maxillarics forming lateral margin of upper jaw. 



a. Adipose tin presi^nt. Pc<rtorals present. 



1. Body naked. Dorsal behind vent, but in advance of anal AsTRoXESTHiD.r 



b. .\dipose tin absent. Peetinals usually present (absent in Photonevtex) Stomiatid.*; 



2. Premaxillaries only forming margin of u))per jaw. 



a. Pectorals rudimentary. Opercula membranaceous. 



I. Body scaleless. Dorsal short, postmcdiau Mal^vcosteid.e 



C. Photophores and barbel absent. 



1. Prenuixillaries forming margin of upper jaw. Faug-likc teeth in mandibles and ])alatine8 

 and sometimes on vernier. 

 a. Dorsal long, occupying entire back. Body naked Ajlkpisauuid^ 



'Absent in /<eHt/io.vnH)«t and sometimes in Bath 



iisaurus. 



