BEKTCID^. 
389 
Acrogaster parvus, Agassiz. 
1838-39. Acroqaster narvus, L. Ao-assiz, Poiss. Foss. vol. iv. pp. 5,134, 
pi. xvii. fig. 1 (?fig. 2). 
1858. Acrogaster parvus, W. yon der Marck, Zeitschr. deutscli. geol. 
Ges. Tol. X. p. 252. 
1863. Acrogaster minutus, W. von der Marck, Palaeontogr. vol. xi. 
p. 23, pi. vii, fig. 1. [Imperfect fish; Academy of Miinster.] 
1863. Acrogaster parmis, W. yon der Marck, ibid. p. 23. 
Type. Imperfect distorted fish; Palaeontological Museum,Munich. 
The type species, imperfectly known by two distorted specimens 
about 0’06 in length. Maximum depth of trunk less than its 
length from the pectoral arch to the base of the caudal fin, and 
about three times as great as the width of the caudal pedicle. 
Dorsal fin with 5 spines and 10 divided rays, the distance between 
its hinder end and the caudal fin equal to the length of its own 
base-line; anal fin with 3 or 4 spines and 10 divided rays, arising 
opposite the middle of the dorsal fin, and the length of its base-line 
nearly equal to that of the latter fin. 
W. von der Marck considers that the scales are enlarged along 
the course of the lateral line. He also regards the second and 
larger specimen, provisionally ascribed by Agassiz to this species, as 
truly representing a distinct form. He erroneously applies the 
name A. parvus to the latter. 
Form. Loc. Hpper Cretaceous: Baumberg, "Westphalia. 
Hot represented in the Collection. 
Acrogaster brevicostatus, W. von der Marck. 
1863. Acrogaster brevicostatus,'^. von der Marck, Palaeontogr. voL xL 
p. 24, pi. vii. fig. 2. 
Type. Hearly complete fish ; Academy of Munster. 
A species attaining a length of about OG. Maximum depth of 
trunk slightly less than its length, and about four times as great as 
the width of the caudal pedicle. Dorsal fin with 3 spines and 14 
divided rays, the distance between its hinder end and the caudal 
fin equalling about half the length of its own base-line; anal fin 
probably with 3 spines and 11 divided rays, arising opposite the 
middle of the dorsal fin, and the length of its base-line approximately 
equal to that of the latter fin. 
Form. Loc. Upper Cretaceous : Sendenhorst, Westphalia. 
Hot represented in the Collection. 
