1884.] NATURAL SCIENCES OP PHILADELPHIA. 165 



AmpWsilids with a spine at the posterior process of the dorsal 

 cuirass. 



Type, A. strigata = Amphisile sp., Klein. 



§ 4. Extinct Families. 



In addition to these types, all represented in the existing 

 faunas, there are two fishes no longer living, which cannot be 

 referred to any of the families as now restricted, but appear to be 

 types of peculiar ones. They are the Urosphen fistularis and Bham- 

 phosus aculeatus of Agassiz ; both have been found in the cele- 

 brated fish-beds of Mount Bolca. These have been referred to the 

 family Fistulariidae by Dr. Giinther, but one of them is more nearly 

 related to the Macrorhamphosidee and Gasterosteidae. They are 

 imperfectly known, but appear to be distinguishable as family 

 t3'pes by the following characters, which will doubtless be sup- 

 plemented by others when well-preserved specimens or character- 

 istic parts shall be critically examined. 



UROSPHENIDiE. 



Hemibranchs with the first four vertebrae much elongate, a 

 moderately elongated body, a long tubiform mouth (ventrals 

 abdominal? dorsal unknown), and a very large cuneiform caudal. 



RHAMPHOSID^. 



Hemibranchs with the anterior vertebra normal (not elongated) 

 and separate, about 22 (8 abdominal and 14 caudal) vertebrae 

 in all, plates on the nape and shoulders only, with a tubiform 

 mouth, subthoracic ventrals, a dorsal spine behind the nuchal 

 armature, and the second dorsal and anal far behind and opposite. 



§ 5. The Pegasidse. 

 Finallj', there is a family which has been shifted from place to 

 place in the system, and which has been referred by Prof. Cope 

 to the order Hemibranchii. Its type was regarded as a chon- 

 dropterygian by Linnaeus and the elders, as a syngnathoid fish 

 by Cuvier ; first isolated in a family by Latreille ; received the 

 family name Pegasidae from H. Adams in 1854 ; was pronounced 

 to be related to the Agonidae by Steenstrup in 1866 ; placed next 

 to them by Giinther (Int., p. 482, 1880), and relegated to the 

 Hemibranchii by Cope. It has also been regarded as the repre- 

 sentative of a peculiar order (" ordo 12. Pegasi "), of the " sub- 



