moodie: cretaceous fishes. 285 



body. The head and opercular apparatus is contained only 

 about twice or at most two and one-half times in the body. 

 From T. magnus it is to be differentiated by the relative pro- 

 portions of the opercular and the skull. The former is con- 

 tained twice in the latter in the present form. In T. magnus 

 it is contained three times. The present species is indeed very 

 closely allied to Thrissopater magnus Woodward from the 

 Lower Chalk of Hollingbourn, Kent. It is to be distinguished 

 by the relative dimensions of the vertebrae as well as by the 

 proportions existing between skull and opercular. The verte- 

 brae in T. magnus are higher than long while in T. intestinalis 

 they are slightly longer than high, and the ends are occupied 

 by distinct rims, such as do not occur, apparently, in the 

 English form. The characters which the two species have in 

 common are striking. They both have the same notch in the 

 anterior end of the mandible ; the same finely punctate ethmoid 

 and nasals; the same form and dimensions of mandible and 

 maxilla; the same divided posterior suborbital; and the same 

 relative shape of skull. Many of these are generic characters. 



The present species can be distinguished from Thrissopater 

 ( ?) megalops Woodward by the proportions of the head. In 

 T. (?) megalops the height of skull from cotylus to supraoc- 

 cipital is equal to the length of the mandible, while in T. is- 

 testinalis the mandible exceeds the height of the skull from 

 cotylus to supraoccipital by 15 millimeters. It may be further 

 distinguished by the relative proportions of the pectoral arch 

 and skull as well as by the absence of the radiately furrowed 

 suborbital and the notch in the anterior end of the mandible 

 in r. (?) megalops. 



Measurements of Thrissopater intestinalis Moodie : 



Length of specimen 29 cm. 



Greatest depth 9 



Length of skull (with opercular apparatus) 9.7 



Depth of skull at quadrate 4.8 



Length of mandible 6 



Depth of mandible at cotylus 1 



Diameter of pharyngeal plate 9 mm. 



Length of tooth 2.5 



Width of opercular apparatus 3 cm. 



Length of clavicle 2.5 



Length of pectoral fin 2.5 



Width of pecoral fin 1.2 



Length of pelvic fin 2.4 



Width of pelvic fin 1.2 



Length of actinost 3 mm. 



Length of dorsal fin as preserved 2.1 cm, 



