OCR Text |
Show 268 MR. A. SMITH WOODWARD O N [Feb. 16, The following papers were read :- 1. On Echidnocephalus, a Halosauroid Fish from the Upper Cretaceous Formation of Westphalia. By A. S M I TH W O O D W A R D , F.Z.S., of the British M u s e u m (Natural History). [Eeceived January 19, 1897.] (Plate XVIII.) In 1858 Dr. W. von der Marck l described a curious eel-shaped fish with well-developed pelvic fins and a separate short dorsal, from the Upper Cretaceous formation of Westphalia. H e gave it the generic name of Echidnocephalus, and in 1863 2 he added to his description some rather sketchy figures of four specimens. In the last-mentioned year Mr. J. V. Johnson presented to this Society3 a description of an existing fish from the seas off Madeira, remarkably similar in general aspect to the extinct form ; and for this he proposed the generic name of Halosaurus, noting the aberrant characters which later induced Dr. Giinther4 to make it the type of a distinct family, the Halosauridas. The striking resemblance between these two fishes does not appear to have been hitherto observed; but, thauks to Dr. Giinther's anatomical investigation of new specimens of Halosaurus obtained by the ' Challenger' Expedition 5, it is now possible to demonstrate that tbe correspondence between the Cretaceous and Becent forms in question is exact even to some of the most specialized osteological features. I have not yet had the privilege of studying the original fossils referred to by Dr. von der Marck, but there are four very fine specimens from the same formation and locality in the British Museum. These form the subject of the following descriptions, and suffice to show very clearly how the strange Halosauroid type was already completely developed before the end of the Cretaceous period. The finest specimen showing the head (Plate XVIII. fig. 1) is a little distorted in the anterior part of the abdominal region, and wants the hinder half of the tail. The head is exhibited in direct side-view, but its structure is very difficult to interpret, most of the bones being shown only in impression, while the opercular apparatus is crushed upon the hyoid and branchial arches, and the pterygo-quadrate arcade upon the more external bones. The cranium is long and narrow and much depressed, as indicated by a fragment of the parasphenoid (pas.) preserved in the orbital region. An impression of the parieto-frontal region suggests that the cranial roof was smooth and gently arched from side to side, without any occipital crest. Below the anterior three-quarters of the skull there is an impression of the pterygo- 1 Zeitschr. deutsch. geol. Gesell. vol. s. (1858), p. 247. 2 Palaeontographica, vol. xi. (1863), p. 55, pl. viii. figs. 1-3, pl. xiv. fig 1. 3 Proc. Zool. Soc. 1863, p. 406, pl. xxxvi. fig. 2. 4 Oatal. Fishes Brit. Mus. vol. vii. (1868), p. 482. 6 A. Giinther, " Eeport on the Deep Sea Fishes," ' Challenger' Reports. vol. xxii. (1887), p. 232, pl. Ix. figs 1-S. ' |