614 The Classification of the Stomiatoid Fishes, 



Parietala present. A small plate-like post-temporal. 



First vertebra normal. Dorsal fin above or 



beliind pelvics 3. Astrotiesthtdcs. 



Parietals absent. No post-temporal. First vertebra ^ 



very long. Dorsal fin well in advance of pelvics. 4, Chauliodontidce ^ 



B. Parietals, post-temporal, supracleitlirum, and mesocoracoid ab- 

 sent. Dorsal and anal wholly or in great part opposed ; no 

 adipose fin ; pectorals usually small or absent. 



Mouth wide ; a hyoid barbel 5. Stomiatidce. 



Mouth very wide ; no barbel ; mandibular sym- 

 physis connected with hyoid by an elastic liga- 

 ment ; no integument between rami of lower 

 jaw 6. Malacosteid(B, 



Family 1. Gonostomatidae. 

 T have examined skeletons of Photichthys (51 vertebrae), 

 GoJiostoma (39 vertebrae), and Maurolicus (34 vertebrae). 

 Other important genera are Cyclothone^ Diplophos, Vinci- 

 guerria, and Ichthyococcus. The last approaches the Sterno- 

 ptychiida3 in the telescopic eyes, the narrow interorbital 

 region, etc., but is essentially Gonostomatid in structure. 



Family 2. Sternoptychiidae. 

 I have examined the skeleton of Argyropelecus (36 

 vertebrae). The other genera are Sternoptyx and Polyipnus, 



Family 3. Astronesthidae. 

 I have studied the skeleton of Astronesthes (47 vertebrae). 

 The other genera are Borostomias (witli spaced maxillary 

 teeth) and Bat hy lychnis (without hyoid barbel). 



Family 4. Chauliodontidae. 

 Chauliodus, the only genus of this family, is remarkable for 

 its formidable dentition. In C. sloanii the vertebrae number 

 58 ; the neural arch of the enlarged first vertebra is 

 represented by long paired laminae. 



Family 5. Stomiatidae. 

 I have examined the skeleton of Stomias boa (78 vertebrae). 

 Most of the other genera (e. g., Macrostomias, Echiostoma, 

 Photonectes, etc.) agree with Stomias in having the body 

 moderately elongate, and the dorsal and anal fins opposed 

 and nearly equal in length, but in Eustomias the anal is 

 longer. Idiacanthus differs from the rest in being very 

 elongate, with the tail long and slender and the dorsal fin 

 longer than the anal. 



Family 6. Malacosteidae. 

 Three genera — Malacosfeus, Fhotoslomias, and Thaumato- 

 stomias. 



