220 GENERATION 



the cavity of the abdomen, should all be brought to these small open- 

 ings, and there make their exit, yet it may not be the less true ; and 

 that this is the most probable way, is still strengthened by [my] having 

 seen the eggs in the lampern [Petromyzon fluviatilis], whose structure is 

 the same [as in the eel], loose in the cavity of the abdomen, in their 

 season for spawning, and other eggs that were not detached, upon the 

 least handling dropped off from the ovaria. 



This structure, although in some respects appearing calculated for the 

 formation of the spawn, yet as that spawn had not been seen and as 

 there was no visible outlet for the spawn when detached belonging to 

 these parts themselves, as is in other fish, it was no wonder that in some 

 minds it remained a dotibt whether they were the parts or not. This of 

 having no outlet belonging to the parts themselves is a curious fact 1 . 



1 [It appears that eels, as a general rule, do not breed in fresh water, but that 

 there are regular migrations of those with milts or roes enlarging, from inland waters 

 to the sea or to the estuaries of rivers, at the end of summer ; and of ' elvers ' or 

 young eels, from those situations to the fresh waters in spring. These, having passed 

 gradually from the brackish or salt to fresh water, ascend streams and drains and 

 spread themselves through the inland waters. The eels descend the river Yarrow 

 to spawn in the end of September. The ' elvers ' ascend the river Connor about 

 the 20th of May, in a slender column about two feet wide, along the edge of the 

 stream. They creep up the wet posts of sluices, and sometimes twist themselves 

 into round balls about four inches in diameter, with their heads turned outward. 

 Mr. Yarrell states that " the passage of the young eels up the Thames at Kingston, 

 in the year 1832, commenced on the 30th of April and lasted till the 4th of May. 

 It was calculated, by two observers of their progress in that year, that from 

 sixteen to eighteen hundred passed a given point in the space of one minute of time." 

 — British Fishes, vol. ii. p. 291. Mr. Yarrell's observations on the oviparous gene- 

 ration of eels, are given in the second series of Mr. Jesse's ' Gleanings in Natural 

 History,' 8vo. 1836. 



A correspondent of Loudon's Magazine of Natural History thus narrates, as an 

 eye-witness, some of the phenomena of the generation of the lamprey: — " On the 

 8th of May I observed a number of lampreys in the act of spawning ; and, remembering 

 the queries of your correspondent, I stood to watch their motions. I observed one 

 twist its tail round another, and they both stirred up the sand and small gravel from 

 the bottom in such a way as convinced me it was a conjunction of the sexes: each 

 sexual conjunction was followed by the ejection of a jet of eggs from the female. I 

 caught them both and dissected them : the sexual organ in the male was projected 

 above a quarter of an inch, and the body filled with milt ; the female, though she 

 seemed to have already shed a considerable quantity of her spawn, had still a to- 

 lerable stock remaining." — Yol. v. p. 745. 



Lampreys drag out stones from the bed of their river by their suctorial mouths, 

 and oviposit in the cavities thus left : the Petromyzon marinus spawn in pairs, the 

 Petromyzon fluviatilis act in concert, forming a common spawning-bed. 



Cuvier repeats the current belief of the hermaphroditism of both the eel and 

 lamprey, and appears to consider the occurrence of a single male lamprey, as noticed 

 by Majendie and Desmoulins, to be an accidental or anomalous circumstance. See 

 the Histoire des Poissons, 4to. vol. i.] 



