during their Growth and Development. Ill 



known in the adult state, and which will no doubt have to 

 undergo reduction. Among the rather numerous small pelagic 

 individuals of the genus Psenes possessed by our museum, I 

 have been able to distinguish five or six species ; but I have 

 onlj partially succeeded in referring them to those which have 

 been described. I regard as new a high, short, and very com- 

 pressed form, nearly colourless and semitransparent, from the 

 Straits of Surabaya, P. pelliicidus^ sp. n. (figured p. 516 of 

 the Danish memoir), which, I suppose, could not very well 

 represent the juvenile form of a Navarchus. Another form 

 very widely distributed in the Atlantic is represented in pi. v. 

 fig. 2 (of the Danish memoir) ; I have made it provisionally 

 a new species under the name of P. maculafus, but strongly 

 suspect that it may be a young form of Navarchus sulcatus 

 {Cuhicejis gracilis), or of Atimostoma capense (species which 

 are perhaps identical), or of some analogous form. We shall 

 hardly deceive ourselves if we regard these three types (P. 

 maculatus, N. sulcatus^ and A. capense) as three successive 

 stages of a single species, or, at any rate, of several very 

 nearly allied species, which only appear rarely at the surface 

 of the sea in their developed state, and which, in consequence, 

 are still but little known to naturalists ; perhaps, indeed, it is 

 not precisely my Psenes maculatus, but another nearly allied 

 form, which I have met with more rarely, and which is dis- 

 tinguished by a smaller number of rays in the vertical fins, 

 that is really the young form of Navarchus sulcatus and Ati- 

 mostoma capense. The group Psenes- Cid>iceps is, in point of 

 fact, one of the pelagic groups of which we know least, and 

 with regard to which we have scarcely begun to lift a little 

 corner of the veil which hides the rich ichthyological fauna of 

 the great depths. In none of these young or more advanced 

 forms of Psenes have I found a spinous prasoperculum as in 

 so many other young Scomberoids, and as is the case in the 

 adult state with the preeoperculum and interoperculum of a 

 fish which appears to be very nearly related to Psenes, namely 

 Palinurichthys [Pammelas) perciformis ; there is nothing 

 which seems to indicate that any of the forms of Psenes that 

 have been described, or that I have examined, can be derived 

 from that species, which is only known from specimens from 

 the eastern coast of North America. 



11. Stromateus, Apolectus ; Schedophilus ; Teachy- 



NOTUS ; MiCROPTERYX ; SeRIOLA. 



The conjecture has already been put forward that the 

 " Rhombus crenulatus^'' Cuv., is a young form of Stromateus 

 alepidotus (Gardenii, longipinnis) . Dr. Giinther has also 



9* 



