CHIEOCEXTRID^, 
101 
P. 6328. Imperfect jaws with remains of the anterior part of the 
cranium, displaying the palatine and prefrontal hones 
and the ossified sclerotic. The articular end of each 
mandibular ramus is also well shown. Purchcised, 1891. 
Ichthyodectes arcuatus. Cope. 
1875. Portheus arcuatus, E. D. Cope, Vert. Cret. Form. "West (Hep. 
U.S. GeoL Surv. Territ. yoh ii.), p. 204 [non pi. xlvii. figs. 7-9). 
1878. Ichthyodectes arcuatus, E. D. Cope, Proc. Amer. Phil. Soc. 
Yol. xyii. p. 177. 
1892. Ichthyodectespolymicrodus, A. R. Crook, Palaeontogr. vol. xxxix. 
p. 112, pi. xvi. [Imperfect skull with jaws; Palaeontological 
Museum, Munich.] 
1892. Ichthyodectes polymicrodus = I. arcuatus, E. D. Cope, Amer. Nat. 
Yol. xxyi. p. 942. 
1898. Gillicus arcuatus, 0. P. Hay, Amer. Journ. 8ci. [4] yoI. yi. p, 230. 
1898. Gillicus polymicrodus, 0. P, Hay, ibid. p. 230. 
1900. Ichthyodectes occidentalis, F. B. Loomis, Palseontogr. yoI. xlyi. 
p. 242, pi. xxiii. figs. 1-6 
Type. Maxilla ; Cope Collection. 
The type species of the so-called Gillicus, with maxilla attaining 
a length of about 0*1. AR bones comparatiyely delicate. Oral 
border of maxilla strongly sinuous, sharply concaye just below and 
behind the palatine articulation; dentarj^ comparatively deep, and 
its oral border slightly concave ; teeth very small, about 100 in the 
maxillary series. 
Form. Loc. Upper Cretaceous (Niobrara Group) : Kansas. 
P. 9201. Vertically crushed cranium and imperfect jaws, associated 
with vertebral centra; Elkader, Logan Co., Kansas. 
Purchased, 1900. 
P. 8902. Fragments of cranium associated with vertebrae ; Elkader. 
By exchange, 1898. 
Ichthyodectes serridens, sp. nov. 
[Plate YIII.] 
Type. Head, &c.; British Museum. 
Head and jaws closely resembling those of I. arcuatus, but 
anterior mandibular teeth relatively larger, and maxilla apparently 
more slender. 
Form. Loc. Albian : Kent. 
^ The extended median dorsal fin in the restoration of this species published 
by Loomis is entirely hypothetical and seems to be based on the erroneous 
assumption that such a fin occurs in Spathodactylus. 
