332 Chronicles of Science. [April 



about 40,000 ova, which were immediately placed in the hatching 

 apparatus. The fish were from three to five years old. 



Professor Agassiz has laid before the Paris Academy a remarkable 

 paper upon the "Metamorphoses of Fishes," which he states are, 

 according to his observations, as important as those of Beptiles (Am- 

 phibia). At the present time, when pisciculture is so much studied, 

 it appears remarkable that such metamorphoses should not have been 

 sooner observed, but Agassiz accounts for it by the fact, that the 

 metamorphoses generally commence immediately after hatching, at 

 which period the fishes die rapidly when kept in captivity. He says 

 he is prepared to show that certain small fishes, which at first resemble 

 Gadoids, or Blennioids, gradually pass to the type of Labroids and 

 Lophioids ; and that certain embryos, similar to the tadpoles of the 

 frog or the toad, take by degrees the form of Cyprinodonts — that cer- 

 tain Apodes are transformed into Abdominal fishes, while some Mala- 

 copterygians (soft-finned) are changed into Acanthopterygians (hard- 

 finned) ; and, further, that a natural classification of Fishes can be 

 founded on the correspondence which exists between their embryonic 

 development and the complication of their structure in the adult 

 state. M. Agassiz lately discovered that the metamorphoses of some 

 members of the family of the Scomberoids are still more unexpected. 

 All icthyologists know the generic characters of the Dory (Zeusfaber), 

 and the peculiarities which attach it to the family of the Scomberoids. 

 Another fish, less known, but more curious, which lives also in the 

 Mediterranean, the Argyropelecus hemigymnus, has been generally 

 classed with the Salmon family, or placed with the salmon as a sub- 

 family. Systemic authors have generally considered the Scomberoids 

 and Salmon as very different fishes, the first being Acanthopterygians, 

 and the second a Malacopterygian. But the Argyropelecus hemigymnus 

 is nothing else than a young Zeus faber. Agassiz says he expects ich- 

 thyologists to declare this opinion erroneous, but, in reply, he invites 

 them simply to compare specimens of Argyropelecus with young 

 Dories, 8 to 10 decimetres in length. 



In connection with the discoveries of M. Agassiz, it may be re- 

 marked that observations of a similar tendency have been made on the 

 Crustacea by M. Gerbe, in conjunction with M. Coste, from which it 

 appears that the larvae of the Palinuri are identical with the species of 

 the curious genus Phyllosoma (glass crabs), possessing the same pecu- 

 liarities, as absence of branchiae, flattened membranous and diaphanous 

 body, &c. There are differences, however, such as the absence of the 

 false feet which are attached to the abdominal segments of the Phyl- 

 losoma, and of the caudal fin of five laminae, which at first would 

 appear to negative the resemblance. But these are only transitory 

 differences, which are effaced in the course of the first four or five 

 changes of skin. All the marine Crustacea, according to M. Gerbe, 

 make their appearance in a larval form, and immediately after birth 

 all of them undergo the first moult. But in no species, not even in 

 the Lobsters, which of all Crustacea are hatched in the most perfect 

 condition, does this first metamorphosis cause the appearance of the 



