THE LONG-SNOUTED CHTMAEKOID OF JAPAN. H 



between the anterior and posterior navial openings. E is 

 attached strongly to skull by ligaments in the region im- 

 mediately above the " premaxillary " dental plates. Also 

 to C, as above noted. The septum is moved notably by 

 means of the element G attached to its posterior eminence. 



G Connected by ligament to the element F and to the 



joint A-G : by fascia to B. 



H A small element attached to the side of F. In this 



region other small elements are to be noted, connected with 

 nasal flap on the one hand and with the upper lip on the 

 other. 



In the structure of the cartilaginous gill arches " Harriotta " 

 again resembles closely Callorhynchus. These elements are figured 

 in lateral and in ventral aspects in PI. L, Figs. 4 and 7. The Sus- 

 pensorium consists of the usual chimaeroid elements, a stout ceratohy- 

 al, a greatly reduced hyomandibular terminating in a small element 

 to which in other chimaeroids various homologies have been ascribed. 

 This element may be regarded provisionally, i.e., until its development 

 is known, as the serial homologue of a pharyngobranchial. Accepting 

 this determination it will be seen that the reduced hyomandibular is 

 coming to establish an articular relation directly with the cranium, a 

 character of considerable importance in vertebrate morphology. Of 

 the remaining five arches the first two are complete, possessing 

 hypobasibranchial, ceratobranchial, epibranchial and pharyngo- 

 branchial elements. The third true gill arch possesses but hypo- 

 branchial and ceratobranchial elements, its pharyngobranchial segment 

 occurring in conmon with that of the fourth gill arch. In the latter 

 arch, what appears to be the somewhat displaced hypobranchial 

 segment probably represents a fusion with the hypobrancnial element 



