184 THE ZOOLOGIST. 
occasions Trout weighing from eighteen to twenty pounds have been taken 
from the Avon near Salisbury. ‘he fish recently taken was a male, and 
had the horny projection of the lower jaw well developed. Is this a mark 
of age, or sex, or both? It is a generally received opinion amongst anglers 
in this locality that its presence denotes an old male, and that its develop- 
ment is increased by a sojourn in fresh water.—G. B. Corsrn (Ringwood). 
[The “horny projection of the lower jaw” is indicative of sex, and is 
peculiar to the male.—Eb.] 
SCIENTIFIC SOCIETIES. 
LinnEAN Society oF Lonpon. 
March 4, 1886. —Sir Joun Lussock, Bart., F.R.S., President, in 
the chair. 
Mr. Gilbert C. Bourne, Mr. William Henry Catlett, and Mr. ‘Thomas 
A. Cotton (N. Z.), were elected Fellows of the Society. 
A paper was read, “ Description of Strongylus Armfieldi, with observa- 
tions on Strongylus tetracanthus,” by Professor Spencer T. Cobbold. Of 
Armfield’s Strongyle, he drew attention to the morphology of the hood and 
its rays, to the position of the vulva, and to the structure of the embryo 
He afterwards contrasted these peculiarities with those of allied forms. 
Regarding his observations on the four-spined Strongyle, the following are 
his conclusions :—(1) The eggs are expelled from their parent in a state of 
fine yolk-cleavage; (2) the embryos are formed after egg-expulsion, and in 
a few days escape from their envelopes, undergoing a primary change of 
skin in moist earth during warm weather; (3) as rhabditiform nematoids 
they enjoy a more or less prolonged existence, probably living many weeks 
in this state ; (4) in all likelihood an intermediary host is unnecessary ; (5) 
the rhabdiform larve are passively transferred to their equine bearers 
either without fresh fodder or whilst the animals are grazing ; (6) passively 
transferred to the intestinal canal, thence they enter the walls of the 
ccecum and colon, encyst themselves, and, according to Leuckart, undergo 
another change of skin; (7) their presence in the intestinal walls is 
associated with pathological conditions, which frequently prove fatal to the 
bearer, sometimes creating severe epizooty ; (8) ordinarily the young worms 
perforate their cysts and migrate to the lumen of the bowel, where they 
already afford external indications of sex (Trichonema stage of growth) ; 
\9) they next form cocoons of the agglutination of vegetable debris within 
the gut and undergo a third ecdysis, attended with intestinal metamorphosis : 
(10) the formation of the internal sexual organs and the completion of the 
definite form is acquired within the colon of the host. 
