THE ORDERS OF TELEOSTOMOUS FISHES 505' 



Superorder Acanthopteroidei (?) 

 (Plate XXIX.) 

 Order Hypostomides 1 Gill 

 The Sea-moths, Pegasidae, are often regarded as an offshoot 

 of the Stickleback-Sea-horse series, and they indeed resemble 

 different members of that assemblage in general appearance, 

 in the possession of a bony exoskeleton, pectinated gills, reduced 

 gill openings, a single dorsal fin, and in the loss of the preoper- 

 cuhim. But Boulenger 2 admits that the supposed relationship 

 with the Thoracostraci is still somewhat doubtful, Gill assigned 

 the group to a separate suborder Hypostomides of the order 

 Teleocephali, following the suborder Acanthopterygii, and Day 3 

 regarded Pegasus as a widely aberrant member of the Gurnard 

 group, a view which seems favored by the following evidence. 

 Pegasus differs from the Thoracostraci in the fact that the greatly 

 enlarged pectorals are not vertical but horizontal , and the mouth 

 instead of being terminal as in the Sea-horses is placed beneath the 

 base of the elongate tubular snout. But these are also points 

 of resemblance to certain of the Agonidae 3 among the cheek- 

 armored Acanthopterygii, with which there is also a general 

 agreement in the characters and arrangement of the dorsal 

 scutes, of the pectoral dorsal and caudal fins, in the dorsal position 

 of the eyes, great reduction of the rays of the dorsal fins, etc. 3 



Order Opisthomi 4 Gill nee Cope 

 The Spiny Eels. 

 (Plate XXIX.) 



These "spiny-finned eels, " forming the family Mastacambelidae,. 

 were mistakenly grouped with the pelagic Notacanths (p. 483),. 



1 vtto, beneath, o"rco//,a, mouth, in allusion to the position of the mouth 

 below the produced snout. 



2 Cambridge Natural History, Vol. VII, p. 629. 



3 Compare the figures of Pegasvis draco in Day, Fishes of India pi. lxi,. 

 fig. 1, and P. natans in Giinther, Introduction, etc., p. 483, with the 

 figures of certain Japanese Agonidae described by Jordan and Starks in 

 Proc. Nat. Mas., Vol. XXVII, 1904, p. 596, especially Podothecus thomp- 

 soni (fig. 11). 



4 OTTiaBev, behind, w/aos, shoulder, in allusion to the backward 

 displacement of the pectoral arch. 



