SOME ASPECTS O F THE BIOLOGY O F THE CHAETOGNATHS
279
in the Red Sea and the lndian Ocean is partially without rays both
on anterior and posterior fins, especially in the median zone of the line
of intersection on the body. This feature, however, is not t o be seen
in Xagitta injlata Grassi in the Atlantic or in the Mediterranean. In
X. injata in the Red Sea and Indian Ocean, the anterior fins may be
longer than the posterior ones (Ghirardelli, 1947).
A further feature one may consider is the length of the caudal
segment in relation to the total length of the specimen. Furnestiri
(1957, 1958) has carried out accurate researches on several species. She
has been able to show that X. setosa which has a wide geographical
distribution and lives in habitats having rather similar characters
(North Sea; Mediterranean, in waters of low salinity; Black Sea),
presents remarkable variations in the length of the tail segment and of
the ovaries, which, however, do not break the unity of the species.
Comparing X. setosa with S. euxina Moltschanoff, she could show that
the latter is only a variety on a larger scale of X. setosa, and since it
lives in the waters of the Black Sea it should be named 8. setosa var.
euxina, though some authors (Alvarifio, 1965 ; Elian, 1960) regard
it as distinct species. The same writer, still on the basis of biometrical inquiries, has further been able to confirm that X. friderici,
though showing features similar to those of S. setosa, is nevertheless a
separate species.
I have myself been able to ascertain (Ghirardelli, 1947) that X.
injata and S . hexaptera of the Red Sea and Indian Ocean, which Thiel
(1938) judged two very near forms if not belonging t o the same species
(he justified the differences he saw as due to a difference in age of the
specimens), must actually be considered as two totally distinct species,
and this mostly on the basis of the proportion between total length
and the length of the tail segment. There naturally are other features
that enable one to differentiate between S. hexaptera and S. injnta" ;
among these are the form of the forward teeth which in X. hexaptera
are always few (three or four at the most), quite elongated and poniardlike. Also the ciliary loop, notwithstanding its great variability with
which I shall deal later, might be a discriminating feature. But at
Naples I have observed (Ghirardelli, 1952) that the two forms of
* Name correct according to Art. 19, 32, 33 of the International Code of Zoological
Nomenclature. Authors generally use Sugittu enflata but Ritter-Zahony (1 908) pointed
out that the Latin word is not enflata, as Grassi (1883) wrote, but inflata, and Baldasseroni (1915) explained further '' per il semplice fatto che in latino non esiste un verbo
enflare ma esiste inflare, quindi influtu e non enJluta " [in Latin the verb is not enflare
but inflare, therefore injZuta and not enflalata]. More recently de Beauchamp (1960) says
" J e ne puis me rksoudre L employer le barbarisme original enJlata " [I cannot bring
myself to use the original bastard form enflatu].
A.llI.B.-6
10
279
in the Red Sea and the lndian Ocean is partially without rays both
on anterior and posterior fins, especially in the median zone of the line
of intersection on the body. This feature, however, is not t o be seen
in Xagitta injlata Grassi in the Atlantic or in the Mediterranean. In
X. injata in the Red Sea and Indian Ocean, the anterior fins may be
longer than the posterior ones (Ghirardelli, 1947).
A further feature one may consider is the length of the caudal
segment in relation to the total length of the specimen. Furnestiri
(1957, 1958) has carried out accurate researches on several species. She
has been able to show that X. setosa which has a wide geographical
distribution and lives in habitats having rather similar characters
(North Sea; Mediterranean, in waters of low salinity; Black Sea),
presents remarkable variations in the length of the tail segment and of
the ovaries, which, however, do not break the unity of the species.
Comparing X. setosa with S. euxina Moltschanoff, she could show that
the latter is only a variety on a larger scale of X. setosa, and since it
lives in the waters of the Black Sea it should be named 8. setosa var.
euxina, though some authors (Alvarifio, 1965 ; Elian, 1960) regard
it as distinct species. The same writer, still on the basis of biometrical inquiries, has further been able to confirm that X. friderici,
though showing features similar to those of S. setosa, is nevertheless a
separate species.
I have myself been able to ascertain (Ghirardelli, 1947) that X.
injata and S . hexaptera of the Red Sea and Indian Ocean, which Thiel
(1938) judged two very near forms if not belonging t o the same species
(he justified the differences he saw as due to a difference in age of the
specimens), must actually be considered as two totally distinct species,
and this mostly on the basis of the proportion between total length
and the length of the tail segment. There naturally are other features
that enable one to differentiate between S. hexaptera and S. injnta" ;
among these are the form of the forward teeth which in X. hexaptera
are always few (three or four at the most), quite elongated and poniardlike. Also the ciliary loop, notwithstanding its great variability with
which I shall deal later, might be a discriminating feature. But at
Naples I have observed (Ghirardelli, 1952) that the two forms of
* Name correct according to Art. 19, 32, 33 of the International Code of Zoological
Nomenclature. Authors generally use Sugittu enflata but Ritter-Zahony (1 908) pointed
out that the Latin word is not enflata, as Grassi (1883) wrote, but inflata, and Baldasseroni (1915) explained further '' per il semplice fatto che in latino non esiste un verbo
enflare ma esiste inflare, quindi influtu e non enJluta " [in Latin the verb is not enflare
but inflare, therefore injZuta and not enflalata]. More recently de Beauchamp (1960) says
" J e ne puis me rksoudre L employer le barbarisme original enJlata " [I cannot bring
myself to use the original bastard form enflatu].
A.llI.B.-6
10