918 proceedings; of the national museum. 



There is such great variety in the foiin of the fourth actiuost (as 

 well as others) in fishes that the objection urged apparently is not of 

 very oreat importance. Even among tlie luiiversally recognized con- 

 stituents of the- group of Ilemibranchs there is great diversity and 

 differences as important as those differentiating the Opah from other 

 fishes exist between the Centriscids or Amphisilids on the one hand 

 and the Gasterosteids and Aulorhynchids on the other. 



The cases of exclusion of rays from the fourth actinost are rare, but 

 by no means confined to the Lampridids. We need, indeed, only look 

 to the Hemibranchs again to find parallel cases. In the genus Aulo- 

 rhi/riclius, as shown l>y Mr. Starks in his excellent article on those fishes, 

 recently publislied, the fourtli actinost is represented as destitute of 

 rays quite as much as that of Lann/pris^ and that of the common Stickle- 

 backs of the north is almost if not quite as much so. In fact, one of 

 the characters of the superfamily (lasterosteoidea would appear to be 

 the nearly or quite complete exclusion of rays from the fourth actinost. 



Such a condition, too, is realized or approximated among Malacopte- 

 rygians {e.. g.^ Salmonids and Esocids or Luciids). It is possibk" that 

 in the excessively modified Opah, deviation from the ordinary type is 

 manifested in such exclusion as well as in other characters and may 

 be the result of mechanical adaptation to the special conditions of 

 position and other modification of the pectoral fin and supporting- 

 bones. 



IV. 



If the views as to the homologies of the bones in (jiiestion are 

 correct, the approximation of LampinH to the neighborhood of the 

 Hemibranchs can not be sustained, as the only ground for it was the 

 supposed homolog}' of the hypocoracoid of the present article with an 

 assumed infrachivicle. The supposititious infraclavdcle (or interclav- 

 icle) of the Hemibranchs has been recently shown, in an excellent paper 

 by Mr. E. C. Starks, to have no independent existence (a conclusion I 

 was forced to come to on scanty material many years ago). The 

 so-called infraclavicle of Lmnpria^ then, has no counterpart among the 

 Hemibranchs. As the supposed agreement of Lamprls with the Hemi- 

 ))ranchs was based mainly on the assumed possession of the same 

 peculiar bone ("infraclavicle") by both t\^pes, the negation of that 

 agreement involves the denial of the relationship. 



But what is the relationship of Lamprisf Cuvier and the elders 

 were perhaps not far out of the way in approximating it to the great 

 Scombroidean series with which it agrees in characteristic modifications 

 of the vertebra? and clasping rays. So far as the scapular arch is 

 concerned, the Caproids agree better than any other known form. 

 Mr. Starks has recently published an article on The Relationship and 

 Osteology of the Caproid Fishes or Antigoniidaj, and given therein 



