474 ZOOLOGY. 



Plata. When the female is preparing to deposit her eggs, she brings 

 together the ventral fins so as to form a pouch which receives them by 

 degrees^ and wherein they are fertilized by the males. The eggs are then 

 deposited in a spot cleaned, by the mouth of the mother, of vegetation. 

 Somewhere about two hundred and fifty eggs are extruded and attached 

 by a viscous coat which envelopes them. The young are developed and 

 able to swim in twelve or thirteen days, but they do not reach maturity 

 till two years after hatching. It is noteworthy that the fishes introduced 

 into France have accommodated their oviposition to the reversed seasons, 

 for, whereas in the Eio de la Plata they lay their eggs in October or No- 

 vember, those born in France matured their eggs in June. 



New observations on terrestrial progression of these fishes have also 

 been published by Mr. Joseph Manson, of Bahia, in " Science" for De- 

 cember 25, 1880. 



A new type of suckers. 



A characteristic family of fishes for the North American fauna is that 

 of the suckers or Catostomidse. Two genera, it is true, are represented 

 in Northeastern Asia; but all the other members of this family are 

 American, and help to impart the stamp of peculiarity to the fish 

 fauna of the United States. Ten genera have been recognized by Jor- 

 dan in his revision of the family, and these are divided into three sub- 

 families, Catostomince, Bubalichthyincc, and Gycleptince. To the first of 

 these is now added, by Professor Cope, a peculiar genas, called Lipo- 

 myzon, the species of which had been previously confounded witli Chas- 

 mistes. They, however, exhibit a difference, especially in dentition, the 

 pharyngeal bones being very slender and flattened, and the teeth min- 

 ute and numerous, as in the carp-suckers. 



Two species are known, both from Klamath Lake, Oregon, the L. 

 luxatus and L. hrevirostris. 



Peculiar eye-like organs in p hy so stome fishes. 



Scarcely any two organs would appear to be more unlike than the 

 eyes of vertebrate animals and the electric organs so highly developed 

 in certain fishes — the torpedos, gymnotus or electrical eel, and mala- 

 pterurus or electrical cat-fish. Nevertheless there are peculiar organs 

 found along the sides of the body, and sometimes on other parts, of 

 sundry pelagic and deep-sea fishes, which have been claimed, on one 

 hand, by different naturalists to be accessory eyes, and, on the con- 

 trary, by others to be rather of the nature of electric organs. Tbe fishes 

 so endowed are mostly of small size and like herring or salmonids in 

 appearance, and were formerly associated in the same family as the 

 latter, but are now referred to several peculiar families — the scopelids, 

 the stomiatids, the chauliodoutids, and the sternoptychids. Generally 

 the organs in question are manifested as pearl-like spots distributed in 

 longitudinal rows along the sides near the abdomen, but they are often 



