272 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



CHIMAERA LiN-NE, 1754, 1758. 

 Six living species of this genus are recognized. 



Chlmaera rnonstrosn Linnc, 1754, 1758. 

 Chimaera phantasma Jordan & Snyder, 1900. 

 CInmaera uffinis Cnpello, 1868. 

 ' Chimaera colliei Lay & Bennett, 1839. 



Chlmaera ogilbi/i Waite, 1898. 

 Chimaera mitsukiirii (Dean) Jordan & Snyder, 1904. 



The sj-nonymy of Chimaera inonstrosa includes C. argentea Ascan., 1772, 

 C. horeaUs Shaw, 1804, C. medilerranea Risso, 1826, C. cristata Faber, 1829, 

 and Callorhynchus centrina and Call, atlantica of Gronow and Gray, 1854 ; and 

 that of Chimaera affinis contains C. plumbea Gill, 1877, and C. ahhreviata Gill, 

 1883. 



Chimaera monxtrosa and C. phantasma have the anal fin distinct from the sub- 

 caudal ; they differ in this respect from the other species. One of the latter, 

 C. colliei, has been made the type of a new genus, Hydrolagua, by Gill, 1862. 

 This genus was originally " distinguished from Chimaera by the absence of an 

 anal fin and the triple division of the sexual organ of the male." The absence 

 of the triple division of the clasper is more apparent than real, since the carti- 

 lage of that organ is trifid in males of all the species of the genus. On 

 Chimaera colliei two of the divisions of the cartilage are wrapped together by 

 the skin so as to present the appearance of a single division. If absence of 

 the anal fin is to make generic separation necessary, then Clmnaera affinis 

 would be placed with C. colliei, though actually farther removed by structure 

 from the latter than C. mnnstrnsa. As may be seen by comparison of the 

 figures published here, in dental characters and in those of the brain and the 

 skeleton Chimaera colliei agrees closely with C. monstrosa. In some respects 

 Chimaera mitsukurii accords with C. colliei, as in the apparently bifid claspers 

 and the lack of an anal fin, but it has a much longer caudal filament than that 

 species. 



The right of Chimaera to be considered the most differentiated of the Chis- 

 mopnea will hardly be questioned. By rostrum, dentition, brain, claspers, and 

 lateral system it is the farthest removed from Rhinochimaera. 



