No-l^JO- ON THE LAMPRinrD.E OR OPATIS—CITLL. 917 



Lavipi'h may be made most evident and the explanation for other 

 views best elucidated l)y the reproduction of Dr. Boulenger's excellent 

 illustration of the shoulder girdle, of the Opah. The names o-ivon are 

 those which are preferred for the present, and the ecjuivalents of Dr. 

 Boulenger follow.-' 



With these identitications the structure of the Opah would be in 

 conformity with that of most acanthopterygians, and the normal num- 

 ber of bones of the scapular arch would be realized. 



The three main bones of the arch (c(Bnosteon, intcrscapiiht. and 

 suprascapula) are developed essentially as usual, and as to them there 

 is agreement with Dr. Boulenger except as to general morphological 

 relations and nomenclature. 



The actinosts or "pterygials," according to the present \ie\v ol" 

 homologies, would also be realized. The almost universal number of 

 four would thus be developed. There seems to me no more difficulty 

 in considering that one actinost ma}'^ be "s3''nchondrosially united with 

 the scapula'' (or hypercoracoid) than that another should be coossified 

 or ' ' fused with '' it. Consequenth^ the complete number of actinosts (4) 

 is recognized, although none is as slightly connected with the snpport- 

 ing bones as usuaL Thus, also, the relative proportions of the various 

 elements of the shoulder girdle and its appendages would be manifest 

 approximately as in ordinary fishes. 



III. 



One objection against the homology of the hindmost (or lowermost) 

 actinost of the Opah with an actinost is urged b3^Dr. Boulenger in the 

 statement " that the posterior of the supposed ptervgials [actinosts] 

 does not support rays and is altogether unlike a pterygial." 



« It might be supposed by one unfamiliar with the intricacies of anatomical nomen- 

 clature, from the difference in the nomenclature of the bones, that the differences 

 between Dr. Boulenger and myself are greater than they really are. The only extra- 

 nominal differences relate to the two bones called coracoid and infraclavicle by Bou- 

 lenger, and hypocoracoid and fourth actinost by myself. I am happy to know that 

 the divergencies respecting the other names are simply the result of different inter- 

 pretations of the same facts from a general standpoint. Dr. Boulenger is the ortho- 

 dox party, inasmuch as he agrees with the majority of anatomists in accepting the 

 nomenclature that has been most current (except in Great Britain) since the time of 

 Gegenbaur. I have to confess to being the heterodox party. But a review of the 

 paleontological and developmental history of the shoulder girdle, as well as of it.-^ 

 comparative anatomy, compels me to reject a nomenclature which appears to me to 

 be extremely misleading. The hypercoracoid and hypocoracoid are only developed 

 in specialized teleost tishes and are (as well as the mesocoracoid ) the results of the 

 ossification and disintegration of a single cartilage occurring in ])rimitive and ganoid 

 fishes and inherited from the Selachians. The application of the names scapula and 

 coracoid, originally given to mammalian part.«, entails a very erroneous and dist<irtcd 

 idea of their relations and history, if it is assumed that the words have any extrin.-^ic 

 meaning at all. 



