ZOOLOGY. 473 



Retinal vessels of fishes. 



Vessels in the retina of the eel have been described by W. Krause as 

 well as by W. Miiller, but on the other hand several competent anato- 

 mists have denied the existence of such vessels in fishes. Dr. G. Den- 

 issenko has, to some extent, reconciled the conflicting statements. In 

 old eels that investigator was unable, like others, to find any vessels, 

 and in old carp, although vessels were found, they were very insignifi- 

 cant, and might easily be overlooked. In the young carp, however, 

 " they occur not only in the innermost layers, but also in the outer 

 granular eye." Dr. Denissenko was consequently led to believe, with 

 Krause, that " with age these vessels usually disappear, in consequence 

 of the growth of the eye forwards and sidewards and the simultaneous 

 extension of the optic nerve. In this way the vessels become com- 

 pressed; their lumen is reduced and finally obliterated." They may 

 thus be developed in the young and atrophied in the old. (J. E. M. S., 

 I, 18, from Arch. Mikr., Anat, xviii, 468-480, with 4 fig.) 



Development of the sturgeon. 



Prof. W. K. Parker has supplemented the important work of Sa- 

 lensky on the embryology of the sturgeon by a memoir " on the 

 structure and development of the skull in sturgeons {Acipenser ruthe- 

 mis and A. sturio) " in more advanced stages. It will be sufficient in this 

 place to indicate that Professor Parker thinks that the cranial scutes of 

 the head are only homologous to the bones of the true osseous fishes in 

 part ; that is, the teleost bones " can only correspond to the inner layer 

 of the scute." But, in addition to others, " along the side of the skull 

 in old individuals, plates of bone appear as splints or parostoses, that 

 are manifestly the forerunners of the deeper plates that, in the higher 

 ganoids and the telostei form the proper ectosteal bony centres of the 

 more or less ossified cranial-box." 



The discovery by Salensky of teeth in the embryonic sturgeon is, of 

 course, confirmed. Larval sturgeons, says Professor Parker, "are, in 

 appearance, miniature sharks. For a few weeks they have a similar 

 mouth, apd their lips and throat are beset with true teeth that are 

 molted before calcification has fairly set in. Their first gills are very 

 long and exposed, but not nearly so long, or for such a time uncovered, 

 as in the embryos of sharks and skates." 



Oviposition of eallichthyids. 



The fact that certain Callichthyids take care of their eggs and young, 

 and are able to progress on land, has long been familiar through the 

 oft-republished observations of Hancock on the so-called Ilassars of 

 Guiana. Eecent experiments by M. Carbonnier, of Paris, (Comptes Ren- 

 dus Acad. Sc, December 6, 1880,) furnish additional details. The in- 

 dividuals experimented with were received at Paris from the Rio de la 



