NOTES—ORIGINAL AND SELECTED.
261
come over here from Holland, etc., but taken with the early movement inland of
the sea-gulls, and the heavy crops of berries all over the country, it is possibly
the presage of a very severe winter."—Westminster Gazette, Oct. 22nd, 1896.
Extracted by Mr. T. H. Wilson.
"The Reproduction and Metamorphosis of the Common Eel (Anguilla
vulgaris)."—A paper by Prof. G. B. Grassi, of Rome, published under the
above title in "The Proceedings of the Royal Society," for December (No. 363, vol.
lx., pp. 260-271), goes far to dispel the mystery which for centuries has enveloped
the life-history of the eel, as well as other members of the Family Muraenidae, and
which is consequently of intense interest to all field-naturalists. In the last century
Pennant described and figured ("Brit. Zool.," 1776, vol. iii., p. 158, pl. xxv.), under
the name of Leptocephalus, a very delicate, eel-like fish, found by a Mr. Morris off
Holyhead, and which has since been occasionally taken off the British coasts.
Since Pennant's time other like forms have been discovered, and the Leptocephali
have been found to be deep-sea creatures, which only occasionally, and by accident
appear at the surface, or in shallow water in an exceedingly languid state, and
frequently much injured. They have been, consequently, but little studied, and
by Dr. Gunther ("Introduction to the study of Fishes"), the Leptocephali were
regarded as the larvae of marine fishes arrested in an embryonic stage, and not as
a normal phase in the development of any species. Fortunately, owing to a certain
set of the currents in the Strait of Messina bringing up volumes of deep water to
the surface, Prof. Grassi has been enabled to obtain an ample supply of specimens
of Leptocephalus brevirostris in a much healthier condition than hitherto, and has
even succeeded in keeping them alive for some time in an aquarium. He has
observed several stages in their development, and has traced their final transform-
ation into "Elvers" (as the young of eels are called in many places), which are
found in spring ascending our tidal rivers, and which ultimately grow into eels.
The cycle of development is therefore complete. In late summer the young eels
migrate to the sea, and, making their way into deep water, become sexually
mature, and deposit spawn. The resulting larvae are the forms known as
Leptocephali, which normally only live in the abysmal waters ; but, as above
described, are occasionally found floating on the surface. Not only has Grassi
traced the development of our common Anguilla, but he has also determined the
cycles of evolution of several other Muraenoids, and amongst them that of the
Conger Eel (Conger conger), the pretty little Leptocephalus morrisii described by our
own Pennant being one of the forms of its larval stages. Prof. Grassi's paper is
indeed a memorable one, and all naturalists will look eagerly forward to the
appearance of the more detailed memoir which he promises.—Ed.
Notes on Essex Butterflies.—I enclose two or three records of uncommon
Essex butterflies, which may be of interest :
Thecla rubi—A few occurred on Woodhill Common, Danbury, during the past
season.
Nemeobius lucina.—One specimen in Slough House Wood, Danbury, very late.
Nisoniades tages.—Fairly common this year on Lingwood Common, Danbury,
which is, I think, an unnoted locality. The specimens vary but little from the
type. I have saved a few of the most divergent for the Club's Museum.—
G. J. Weeks, Elm Cottage, Chelmsford, December 10th, 1896.
Prionus coriarius at Chelmsford.—I have a female specimen of this fine
Longicorn beetle, taken at "sugar" this year at Waterhouse Lane, Chelmsford.—
G. J. Weeks, December 10th, 1896.