20 ART. 4.— BASHFOED DEAN. 



a key to the relationships of its group. An examination of allied 

 Pacific species, however, demonstrates, as we have seen, that such ex- 

 pectations are not to be realized, ank that this form of Chimaeroid is 

 to be looked upon as of no greater value than the hetter known 

 genera. Even its skull structure is not convincingly primitive, for 

 certainly little stress can be laid upon the distinctness of the palato- 

 quadrate suture in one specimen when it is altogether lacking in a 

 second one. In some regards, on the contrary, this chimaeroid is 

 sven furthest away from our conception of the ancient form, e.g. in its 

 highly specialized rostral and labial cartilages, its greatly produced 

 enout and tritorless dental plates,* its coalesced gill supporting 

 elements, its compressed paired fins, its more perfectly obliterated 

 mesenteries. And so far from possessing no well marked clasping 

 organs, it has them in a condition of high specialization ; thus in the 

 case of the mixipterygium I have evidence that three supporting 

 olements of the other chimaeroids are present, but have undergone a 

 process of coalescence, to the degree of producing a narrow and 

 eelicate appendage, bulbous at the tip, and provided with fewer and 

 arger denticles than in other forms. Moreover, as there is reason to 

 lelieve that this type of chimaeroid is from deeper water than the 

 bther members of the group, we can hardly expect that its further 

 study will yield convincing data as to its primitiveness. In its egg- 

 dase it is as highly specialized as Callorhynchus. 



* From Garmau's preliminary note he is evidently of the opinion that the tritorless condi- 

 tion is primitive in t lie dental plates of chimaeroids. This rather startling view ; — for without 

 further explanation, it implies that the dental plates are not to be derived from elasmobranchian 

 (onditions, — is based upon two untenable premises: (1), resemblance to the dental plates of 

 cTrias or Jura) myriacanthe, and (2), similarity to the very early conditions of the teeth 

 of other living Chimaeroids. The first of these premises is, I am convinced, based upon a 

 misconception of the dental character« of Myriacantlvu*, in which many tritoral areas are 

 present; the second upon an interesting larval ism which the young plates present, growth 

 occurring precociously at one rim of the plate. From jtfy study of the development of 

 Chimaera colliei I am led to believe' thai 'the dental plati s of Rhinochimaera persist in a larval 

 fcondition : they have never passed through the stage represented in Harriotta, and the two 

 forms are thus more than generically distinct. The latter genus is, therefore, tobe removed 

 rom the Rhinochimaeridae, and becomes the type of a new iamUj-Harriottidae. Upon 

 Harriotta the writer has in preparation a separat paper. 



