456 WILLIAM K. GREGORY 



Order Hypostomides Gill » 



Fam. Pegasidae 

 Order Opisthomi Gill 



Fam. Mastacambelidas 

 Order Pediculati Gill 2 

 Fam. Lophiidas 

 " Ceratiidas 

 " Antenariidae 

 " Gigantactinidae 

 " Malthidas 



Infraclass CROSSOPTERYGII 3 Cope. 



"These forms appear in the Upper Devonian, flower out in 

 the late Palaeozoic, and one group, the Coelacanths, persists 

 almost unchanged throughout the whole series of formations 

 from the Lower Carboniferous to the Upper Chalk" (Woodward). 



The superorder is sharply distinguished from the Actinopteri 

 by the following assemblage of characters, (i) The paired fins 

 are lobate, 4 i.e., with a cartilaginous axis, scaly externally and 

 fringed on both sides by dermal rays. (2) The dorsal and anal 

 fins are remarkably analogous to the paired fins in form and 

 probably in function, and in the relations of the dermal rays to 

 the endoskeletal supports; the median fins usually lack the 

 numerous supporting fin fulcra so characteristic of the primitive 

 Actinopteri. (The Osteolepidce however exhibit modified enamelled 

 anterior ridge scales which resemble the fulcra of higher forms.) 

 (3) The axonosts of the dorsal and anal fins exhibit various 

 degrees of coalescence, so that finally the paddle-like median 

 fins probably enjoyed a high complexity and independence of 

 movement. (4) There are two dorsal fins in the primitive forms. 

 (5) The tail fin, in the earliest forms heterodiphycercal, often 

 coalesces with the posterior dorsal and anal fins into the gephy- 

 rocercal form. 5 (6) A spiracle is present. (7) The distal end 



1 Incertas Sedis, see page 505; may be only a division of the Acanthop- 

 terygii Pareioplitae. 



2 Families as denned by Boulenger. 



3 (npoddoi, tassels, a fringe, itTEpvytov, a little wing, fin, in allusion to 

 the tassel-like pectoral fins, or to the fringe-like dorsals of Polypterus.) 



* Except possibly the ventral fin of Eusthenopteron and its allies. 

 5 See Appendix II. 



