34 FOSSIL FISHES OF THE ENGLISH CHALK. 



indeed, very suggestive of the latter genus ; though Auhpus is proved to differ 

 from the typical species of Sardinioides by its more numerous vertebrae (total 50), 

 and by the elongation of some of its dorsal fin-rays. Chlorophthalmus (Text-fig. 7) 

 is also an allied existing genus. 



1. Sardinioides illustrans, sp. nov. Plate X, fig. 1. 



1901. Sardinioides, sp. ind., A. S. Woodward, Catal. Foss. Fishes B. M., pt. iv, p. 242. 



Type. — Imperfect fish from English Chalk ; British Museum. 



Specific Characters. — A robust species, attaining a length of about 20 cm. Im- 

 perfectly definable, but probably most closely resembling the type species, 

 S. monasteri, with more feebly pectinated scales. 



Description, of Specimens. — This species is known only by the type specimen 

 (PI. X, fig. 1), and by an imperfect head in the British Museum. It is therefore 

 not 3^et precisely definable. 



As shown from above (PI. X, fig. 1) the cranium is short and broad, with a 

 flattened roof and wide interorbital region. The occipital border is straight, and 

 the hinder face of the small supraoccipital bone bears a low median crest {socc), 

 which does not rise above the plane of the cranial roof. The thickened epiotic 

 angles {epo.) project through the scales in the fossil. The short and broad parietal 

 bones {pa.) meet in the median line, and that of the left is larger than that of the 

 right side. The small squamosal and postfrontal bones must have partly covered 

 the otic region, of which the roof slopes downwards and outwards on each side. 

 The postfrontal (p//.) is a narrow curved plate of bone, with its long axis directed 

 at right angles to that of the cranium. The frontals (/r.) are remarkably broad 

 throughout their length, and meet in a wavy median suture. There is a slight 

 depression in their middle part, and they are traversed by a pair of very large 

 longitudinal slime-canals. Each frontal is expanded over the hinder half of the 

 orbit into an extensive supraorbital flange, which terminates suddenly in front and 

 is continued by an antero-posteriorly elongated supraorbital bone (sph.). This 

 region has been cut away in the second fossil in the British Museum (no. 49057). 

 Beneath the truncated anterior end of the frontals, the short and broad mesethmoid 

 (rfh.) projects slightly forwards. Its front border is thickened and excavated by 

 a slight re-entering angle, beneath the middle of which there is a little bony 

 prominence. A pair of very small, long and narrow nasal bones {iix.) can also be 

 distinguished. All these bones, except the inesethmoid and nasals, bear a very 

 delicate ornament of radiating wrinkles or ruga?. 



The eye is shown to have been rather large and surrounded by a narrow ring 

 of circumorbital plates. All these are imperfect in the type specimen, but the fore- 

 most plate of the ring is relatively large, and must have completely covered the 



