488 
ACT1N0PTERYGII. 
Poiss. Foss. vol. v. pt. ii. (1844), p. 139, and llep. Brit. 
Assoc. 1844 (1845), p. 307. Egerton Coll. 
P. 1741. Similar cranium with mandibular suspensorium, and frag- 
ments of mandible and opercular apparatus. Egerton Coll. 
33136, 35692. Two imperfect crania. Purchased, 1858-59. 
Genus HEMIRHYNCHUS, Agassiz. 
[Poiss. Foss. vol. v. pt. i. 1844, p. 87.] 
Syn. Homorhynchus, P. J. Van Beneden, Bull. Acad. Roy. Belg. [2] 
vol. xxxv. 1873, p. 210. 
Head as in Palceorhynchus, but slender rostrum about twice as 
long as mandible. Vertebrae about 25 in the abdominal, 28 in the 
caudal region. Pectoral fins small and delicate ; pelvic fins larger ; 
dorsal fin extending almost the whole length of the back, its rays 
about twice as numerous as the vortebr® ; anal fin also very ex- 
tensive, with rays much moro numerous than the vertebrae ; caudal 
fin forked. Dorsal and anal fin -supports as in Palceorhynchus. 
Hemirhynchus deshayesi, Agassiz. 
183!). Histiophorus deshayes, L. Agassiz, Poiss. Foss. vol. v. pi. XX X . 
1844. Hemirhynchus deshayes, L. Agassiz, Poiss. Foss. vol. v. pt. i- 
p. 88. 
1852. Hemirhynchus deshayes, P. Gervais, Zool. & Pal. Frau?., Poiss. 
Foss. p. 7, pi. lxxi. figs. 2, 3. 
Type. Imperfect distorted fish ; Paris Museum of Natural 
History. 
The type species, attaining a length of about 0'45. Maximum 
depth of trunk contained about eight times in length from pectoral 
arch to base of caudal fin. 
Snout incomplete in known specimens. 
Eorm. Loo. Middle Eocene (Calcaire Grossier) : Paris. 
Not represented in the Collection. 
Hemirhynchus colei (Agassiz). 
1842-44. Palaorhynchum egertoni ', L. Agassiz, Poiss. Foss. vol. v. 
pt. i. p. 80, pi. xxxiv a. fig. 1. [Imperfect fish ; British Museum.] 
1842-44. Palceorhynchum colei 1 , L. Agassiz, ibid. p. 85, pi. xxxii. 
fig- 1. 
-These) specific names were firBt published without definition in Egerton’s 
Catal. Foss. Fish, 1837. 
