during their Growth and Development. 3 



In the following summaiy of tlie principal facts and results 

 which are set forth in my memoir, I have followed the order 

 of the chapters in the Danish text. 



1. Dactylopterus and Cephalacanthus. 



As is well known, M. Canestrini has endeavoured to prove 

 that Cephalacanthus spinarella {Pungitius _pusillus) is the 

 young form of Dactylopterus. This opinion was apparently 

 well founded ; but it has been contested by M. Steindachner, 

 principally with the argument that we may meet with Dactij- 

 lopteri a little smaller than the largest of those which still pre- 

 sent the characters of Cephalacanthus. Having had at my 

 disposal, on the one hand, a series of twenty-five specimens of 

 Dactylopterus volitans of all sizes, from 380 to 47 millims. 

 in length, the last with the wings still short, and, on the other 

 hand, almost as many of Cephalacanthus spinarella (twenty- 

 three), also of all sizes, from 49 to 8 millims. long, I have 

 studied in these two series all the characters subject to modi- 

 fications arising from differences of age, in order to discover 

 whether the changes which the Cephalacantlii had undergone 

 enabled us to ascend to the Dactylopteri, and reciprocally 

 those of the latter to descend to the Gephalacanthi.^ or whether 

 these fishes constituted two series of forms independent of 

 each other. The result of these comparisons (for the details 

 of which I must refer the reader to the Danish memoir) has 

 been, so far as I am concerned, an absolute confirmation of 

 M. Canestrini's hypothesis. We may certainly find Cepha- 

 lacanthi a little larger than the smallest Dactylopteri '^ but 

 this is easily explained by the fact that the metamorphosis 

 properly so called, which no doubt takes place comparatively 

 quickly, does not always occur precisely when the young fish 

 has attained a definitive length (about 50 millims,), but may, 

 according to circumstances, occur in a given individual a little 

 sooner or a little later. It may be added that the localities 

 (latitude and longitude) where our young Dactylopteri or so- 

 called Cephalacantlii were taken seem to prove that this 

 genus possesses the character of a semipelagic genus in a 

 greater degree than has hitherto been supposed. It appears 

 also, from the investigation that I have made of its develop- 

 ment, that the small anterior part of the pectoral fins in 

 Dactylopterus is, properly speaking, the superior and not the 

 inferior part, as has hitherto generally been stated, 



2. Ehynchichthys, Rhinoberyx, and Rhamphoberyx ; 

 HoLOCENTRUM and Myripristis. 



The hypothesis has already been advanced that Bhynchich- 



1* 



