helo)i<jin(j to the Faiiiili/ rv/\Sqiianiipimies. 



319 



were considerably larger, viz. 1^^ inch long- (= 28 millims.). 

 Although they retained the peculiar armature of the head, the 

 form of the body and lins liad greatly changed, resembling 

 now that of a Gho'todon or Holacantkus ; so that Mr. Day felt 

 convinced that Tholichthys was the young of a genus of 

 Sqiiamijnnnes (Proc. Zool. Soc. 1870, p. 687). 



It is my object in the present notice to show that this sup- 

 position of Mr. Day is quite coi-rect. Unfortunately the spe- 

 cimen deposited by Mr. Day in the British Museum has been 

 mislaid, so that I cannot avail myself of it for comparison 

 with the specimens Avhich I intend to describe here. 



1. I have examined two specimens, 30 millims. long, of 

 Chretodon citrinelliis — one, in the British Museum, from the 

 Feejee Islands, and the other recently obtained from Hr. C. 

 Godeffroy. These examples show all the characters of 

 that species : not only are the fins as 

 well developed as in the mature form, 

 but also the black ocular band and 

 the marginal anal stripe are present. 

 Yet these specimens still retain the 

 scapulary and humeral larainfe, and 

 the prteopercular process projects to 

 the root of the ventral. Compara- 

 tively, these laminffi appear to be smaller than in ThoUchthyes of 

 younger age ; but this is merely in consequence of the greater 

 development of the body in the more advanced stage, its 

 growth being much more rapid than that of the head. 



2. Not only Chcetodon, but also other Squamipinnate ge- 

 nera appear to have a TIwUchthys-stRgc. With the speci- 

 men of Ch. citrinellus mentioned above, Hr. Godeifroy sent 

 another fish, represented in the accompanying woodcut, and 

 now in the British Museum. The 



plates on the shoulder and prteoper- 

 culum are as in the young of Ghce- 

 todon ; but the fish is distinguished 

 besides by a remarkably long and 

 curved horn above each orbit; a 

 deep groove runs along the lower 

 side of the horn. The numbers of 

 the fin-rays are, D. 1| and A. ^. 

 There are between 50 and 60 trans- 

 verse . series of scales on the body. 

 Now,' although it is possible that the 



horn above the orbit is also an excrescence lost in the more 

 mature state of the individual, it yet reminds us of those 

 species of Heniochus which arc provided with more or less 



