120 Mr. C. T. Regan on the Anatomy and 



XIII. — The Anatomy and Classification of the Teleostean 

 Fishes of the Order Iniomi. By C. Tate ReGAN, M.A. 



(Published by permission of the Trustees of the British Museum.) 



The Iniomi are marine malacop.terous physostomes with the 

 pelvic fins abdominal or thoracic in position and the pelvic 

 bones free from tiie cleithra ; an adipose dorsal fin is typically 

 present, the prsemaxillaries exclude the maxillaries from the 

 gape, the gill-openings are wide, tiie pectoral arch is attached 

 to the skull by a forked post-temporal, there is no meso- 

 coracoid, the vertebral centra are coossified witli the arches, 

 the air-bladder is small or absent, and the ovaries are pro- 

 vided with oviducts. 



The families Rondeletiidse and Cetomimidse are known, 

 only from a few specimens taken in deep water; they pre- 

 sumably pertain to this order, for the prsemaxillaries form 

 theu})per border of the mouth, but tliese fishes differ from the 

 rest in the posterior position of the dorsal fin, which is 

 opposed to the anal. Tiiey will probably form a distinct 

 suborder when they are better known. 



Of the Cretaceous fishes which may pertain to the Iniomi 

 the Chirothricidaj are probably related to the Aulopidse or 

 Sudidge, but the Enchodontidge appear to me to show more 

 agreement with the Stomiatidse than with the Alepidosauroids, 

 to which Smith Woodward considers they are related. The 

 Dercetidge are of uncertain relationships, but the orbital and 

 postorbital parts of the skull and the post-temporals show 

 considerable resemblance to Evermanella (^Odontostomus), 

 whilst the ethmoid region and jaws are more like those of 

 Alepidosaurus. Of the fishes placed by Smith Woodward 

 in the Scopelidas many are of very doubtful position, but 

 Sardinioides crassicauda and illustrans certainly belong* to 

 the Aulopidae. Other species referred to Sai-dinioides re- 

 semble .Neoscopelus or Ch/orophthalmus, to which Acrognathus 

 may be related. Apateodus is probably near Alepidosaurus. 

 The skeletal characters of the Iniomi have not hitherto 

 received mucli attention. Giintlier has figured the pectoral 

 arch of Omosudis and £athyj)terois (' Challenger ' Deep-.eea 

 Fishes). Gill has pointed out that in several families the 

 post-temporals " impinge upon the occiput." Smitii Wood- 

 ward has figured the head skeleton of Aidopus for coxmpax'ison 

 with Sardinioides (Palseontograph. Soc. 1902). 



' 



11 



