ACIPEXSERID2E. 
43 
Genus ACIPENSER, Linnaeus. 
[Syst. Nat. ed. 10, 1J58, p. 237.] 
External bones ornamented with tuberculations of ganoine. Jaws 
delicate, and minute pointed teeth present only in very young 
individuals] spiracles present. A few slender ribs. Pectoral fins 
with a robust anterior ray or spine ; pelvic, dorsal, and anal fins 
remote, the two latter opposed; caudal fin inequilobate, extending to 
the extremity of the upper caudal lobe. Dermal scutes in five 
distinct series, one dorsal, two pairs lateral, not completely envelop¬ 
ing the caudal pedicle. 
Numerous scutes, pectoral spines, and fragments of bone indis¬ 
tinguishable from the corresponding parts of the existing Acipenser , 
are known from Tertiary formations; but no examples sufficing for 
specific diagnosis have hitherto been discovered. A brief enumera¬ 
tion of the known fossils is given below. 
Acipenser toliapicus, Agassiz, MS. 
1844. Acipenser toliapicus, L. Agassiz, Poiss. Foss. vol. ii. pt.ii. p. 280 
(name only). 
1889. Acipenser toliapicus, A. S. Woodward, Proc. Geol. Assoc, vol. xi. 
p. 28, pi. i. fig. 1. 
Type. Imperfect scutes ; British Museum, 
A provisional name given to the earliest known scutes of Acipenser 
from the London Clay. The external surface is very deeply pitted, 
and the reticulations are nodose. 
Form. Sf Loc. Lower Eocene (London Clay): Isle of Sheppey. 
P. 3372. Two dorsal scutes intended by Agassiz to be the type 
specimens of the species, one labelled by that author, the 
other described and figured by the present writer, loc. cit. 
Enniskillen Coll. 
P. 529. Somewhat larger scute, labelled by Egerton as a type speci¬ 
men. Egerton Coll. 
37762. Well-preserved portion of another scute. Purchased , 1863. 
24619. Imperfect left infraclavicle exhibiting very deep pits between 
the reticulations on the exposed outer face. 
Purchased , 1850. 
44093. A less imperfect, larger example of the right infraclavicle 
0*115 in length, showing the smooth inferior margin. 
Both in this and the previous specimen the external 
