4 Dr. C. F. Liitken on the Changes of Form in Fishes 



tJn/s pelamidis, C. & V., and other species of Rhynchichtliys 

 subsequently established are young Holocentra (or Myri- 

 pristes) ; and the correctness of this view is now confirmed by 

 the circumstance that it has been possible to refer several small 

 examples of " Rhynchichthys'''' and '•'' B.hinoberyx'''' of diffe- 

 rent ages, fished in the western part of the intertropical 

 Atlantic, to a definite species of Holocentrum, the H. maria- 

 num of the Antilles, which, however, has hitherto been very 

 imperfectly described. We are acquainted with it now in all 

 the phases of its development : — as the true Holocentrum ^ young 

 and adult ; as " Rhinoheryx^'' a phase intermediate between 

 the HoJocentrum and the " Rhynchichthys ;" and, finally, in 

 this last and very young state. 



In the Danish memoir I have described in much detail the 

 characters of the species in each of these phases, comparing 

 them both among themselves and with the corresponding 

 states of HoJocentrum soyho, another common West-Indian 

 species, of which we possess an almost equally complete series 

 of forms. The " Rhamphoheryx " is probably the corre- 

 sponding young form of Myriiwistis. These three genera 

 {Rhynchichthys^ Rhinoheryx, and Rhamphoheryx) must there- 

 fore be suppressed, with the species belonging to them ; and 

 we may say the same of certain species such as Holocentrum 

 platyrhinumj which are also young forms of which the trans- 

 formation is not completed, but which, instead of being referred 

 to separate genera, have only been placed in a special group 

 of the genus Holocentrum. 



But at the same time I have been able to recognize a phase 

 of development anterior to that which serves as the basis of 

 the genws, RJiynchichthys. A small fish, 7 millims. long, which 

 is undoubtedly the young form of a West-Indian Holocentrum^ 

 perhaps even of H. vuirianum, is distinguished from the true 

 " Rhynchichthyes " by a forked beak, the comparatively great 

 length of which is equal to twice the diameter of the eye, and 

 by the occipital spine, which is very strongly developed, as 

 well as those of the prasoperculum, which last extend much 

 beyond the ventral fins, as far as the middle of the anal. Our 

 museum possesses very young larvae of Berycidge (that is to 

 say Rhynchichthyes) from the Indian Ocean, which much re- 

 semble the preceding form ; but in others, which otherwise 

 have an analogous structure, the beak, which is sometimes 

 comparatively short and sometimes extremely elongated, does 

 not present the remarkable division in the form of a fork. 

 Considering the numerous representatives of this family in the 

 Indian seas, it is impossible at present to determine these 

 young forms more exactly. 



