HEMIBRANCHII. 
369 
Sphytxena Sternberg ensis, T. C. Winkler, Archiv Yereins Fr. 
Naturg. Mecklenburg, rol. xxix. (1875), p. 123, pi. iii. 
figs. 17, 18. — Upper Oligocene ; Sternberg. [Jaw and 
scale.] 
Spkyrcena to inkier i, It. Lawley, Nuovi Studi Pesci, etc. Colline 
Toscane (1876), p. 77. — Lower Pliocene; Orciano, Tus- 
cany. [Teeth.] 
The so-called Sphyrama amici (L. Agassiz, Poiss. Foss. vol. v. 
Pt. i. 1843-44, p. 97, pi. x. fig. 3) is founded on remains of a skull, 
not of this genus, from the Upper Cretaceous of Mount Lebanon. 
With the Percesoces are sometimes placed the Ophiocephalid.e, 
a family of freshwater fishes common in the Indian region, rarer 
in Africa. No extinct representatives are definitely known, but 
the following fossils have been referred to the existing genus 
Ophiocephalus : — 
15374-75, 16402,-a. Four fragmentary heads ; Siwalik Formation 
( Pliocene), Siwalik Hills, India. Noticed by It. Lydekker, 
Palaeont. Indiea, ser. x. vol. iii. (1886), p. 246, the third 
specimen being figured, loc. tit. pl. xxxvii. fig. 2, also 
noticed by J. M‘Clelland, Calcutta Journ. Nat. Hist, 
vol. iv. (1844), p. 83. 
Presented by Col. Sir Proby T. Cautley, K.C.B., 1S42. 
Suborder VIII. HEMIBRANCHII. 
^ ertebral centra always complete constricted cylinders, those 
immediately behind the occiput more or less modified or coalesced. 
Supraoccipital extending forwards between the reduced parietals : 
squamosal rudimentary and fused with the largo pterotic ; mandible 
simple, each ramus consisting only of two elements (dentary and 
articulo-angular). branchial arches always more or less reduced. 
Pectoral arch suspended from cranium ; large infraclavicular plates 
present ; pectoral fin with not more than four or five basals. 
I elvic fins usually abdominal, but sometimes advanced so that their 
supports are in contact with the pectoral arch. Dorsal fin with 
without an anterior spinous portion. In the living forms : — 
air-bladder closed, without pneumatic duct, in the adult (physo- 
clistous) ; optic nerves decussating ; intestine without spiral valve. 
U ollowing the suggestions of liner and Steindachner and Cope 2 
1 Detiksehr. k. Akad. Wiss., math.-naturw. Cl. vol. xxi. (1863), p. 28, footnote. 
F. D. Cope, Origin of the Fittest (1887), p. 328. 
I* art iv. 2 B 
