12 ART. 4.— BÄSHFORD DEAN. 



of the fifth arch as well. The fifth arch, rudimentary, exhibits a 

 cerato- branchial, and a greatly reduced pharyngobranchial in the 

 shape of a discrete tubercle of cartilage attached to its dorsal terminal. 

 The unpaired median series of ventral cartilages is poorly represented. 

 A basihyal is closely moulded to a stout hypobranchial, and this alone 

 of the median elements is directly articulated with an arch. It is 

 stoutly attached to the ceratohyal. I note also a pisiform cartilage 

 which is attached by ligament to the hypobranchial of the third gill. 

 The posterior median element is a stout ensiform plate attached by 

 a broad ligament to the common hypobranchial of the fourth (and 

 fifth ?) arch and to the ceratohyal of the fifth arch. 



Vertebral Column. 



As in other chimaeroids, the notochord is strengthened by calci- 

 fied rings occurring within the notochordal sheath. Xeural and 

 haemal arches, however, are represented throughout the anterior 

 three-quartors of the column. In the region of the anterior half of 

 the column there are neural and interneural cartilages. On the 

 ventral side of the chorda, appear haemal plates more or less irregular 

 in size, and often exhibiting fusion. These characters are well shown 

 in PI. I., Fig. 4. In the block-like portion of the column which 

 immediately follows the skull a number of foramina are present for 

 the dorsal and ventral narve-roots. The openings, representing 

 about twelve nerves, are obviously crowded together and afford 

 conclusive evidence that a considerable shortening of the column has 

 taken place, especially in the more anterior region. Furthermore, 

 according to the relations of the posterior portion of this plate to the 

 adjacent neural and interneural plates, one can f -I believe, safely infer 

 that the dorsal expansion of this compound element is equivalent to 



1) Similar conditions occur in C. colliei. 



