274 



APPENDIX. 



No. IX. 



mens taken in Discovery Bay throws considerable light upon 

 this question. 



In this individual the dental armature consists of four teeth 

 regularly superposed, following upon which, and occupying the 

 same breadth as a tooth, are three ossicles, which fit to one 



another wedge wise with sloping- 

 sides. Then come two which 

 fit together and correspond in 

 their shape with the irregu- 

 larities of the upper and under 

 tier, which latter consists of 

 from three to five compact 

 close-fitting papillae ; and these 

 again are succeeded by three 

 or four (in some rays five) 

 moderately long, round-tipped, 

 smaller papillae, the whole 

 forming a compact mass sug- 

 gestive, in the highest degree, 

 of ordinary tooth-papillae, such 

 as occur, for instance, in Ophio- 

 thrix ; and yet in every detail, 

 even to measurements, the specimen conforms to the diagnosis 

 of Ophioglypha, Sarsii. This individual has a disk-diameter 

 of 22 millims. 



Bearing in mind the tendency towards vertical redupli- 

 cation of the mouth-papillae in some genera, this cannot fail 

 to be regarded as suggestive of the manner in which primitive 

 tooth-papillae may have been developed ; nor is such an 

 assumption by any means extravagant when the great irregu- 

 larity of these parts amongst Arctic forms is taken into con- 

 sideration. 



w.p.s 



Abnormal development of the 

 dental armature in 0. Sarsii. 



Ophioglypha robusta (Ayres), Lyman. 



Coll. Feilden : Discovery Bay, 25 fms., hard bottom ; 

 Richardson Bay, 70 fms. ; Hayes Point, 35 fms., bottom tern- 



