468 DK. W. G. EIDEWOOD ON THE CRANIAL [DeC. 13, 



In the first two branchial arches the epibranchial is longer 

 than the ceratobranchial, but in the third the reverse is the case. 

 The third hypobranchials are small and concealed in a dorsal 

 view by the breadth of the posterior end of the third basibranchial. 



oh. 



sp 



pW 



-cf 



0b f- 



Chatoessus erehi, hyobrancliial skeleton, dorsal view.— The epibranchials and 

 pharyngobranchials of tlie right side are not shown. For explanation of 

 lettering see p. 493. 



Whereas in most forms the fourth pharyngobranchial is repre- 

 sented by a cartilage with a removable dentigerous membrane- 

 bone on its ventral surface, in Chatoessus the membrane-bone 

 (devoid of teeth) flanks the cartilage on three sides, ventral, 

 mesial, and dorsal, and simulates an ossified fourth pharyngo- 

 branchial. The first pharyngobranchial is cartilaginous, and a 

 large spicular bone is present. There are no teeth on any part 

 of the hyobranchial skeleton. 



DUSSUMIERIA ACUTA. 



Material examined. — In addition to a skull specially prepared 

 for the purposes of this investigation from an alcohol-preserved 

 specimen from Madras kindly furnished by Mr. G. A, Boulenger, 

 another skull was examined, belonging to a complete skeleton in 

 the Osteological Collection of the British Museum (Brit. Mus. 

 1889.2.1.2038, Bombay). 



Cranium (text-fig. 1 30, p. 469). — The cranium has all the cha- 



