8
THE BIOLOGY O F EUPHAUSIIDS
species Thysanopoda krohnii and T . longipes were described by Brandt
(1851).
Another species of Thysanopoda was described by Bell, who in 1853
published his History of the British stalk-eyed Crustacea. He included
the genus Thysanopoda, with the characteristics given by MilneEdwards, in the family Mysidae. He added a note to the effect that the
eggs were contained in a pair of oval sacs dependant from within the
bases of the posterior feet and so differing from those of other mysids.
Bell’s species was Thysanopoda couchii (now Nyctiphanes couchii),
large numbers of which were taken from the stomach of a mackerel
caught in the English Channel.
At a meeting of Scandinavian biologists held in Christiania (now
Oslo) from 12-18 July, 1856 the great Norwegian zoologist Michael Sars
described three new crustaceans (Sars, 1857). One of these represented
a new mysid genus and was called Lophogaster typicus; the other two
were species of Thysanopoda, T . apiops and T . norvegica (now
Meganyctiphanes norvegica). Sars obtained four specimens of Thysanopoda norvegica from Floro and Sondfjord in Norwegian waters. They
were about 2.5-4.0 cm in length, of which the cephalothorax formed
about one-third. He also had a further nine specimens from the guts of
two Norway haddocks, Sebastes norvegicus (=S. marinus (L.)), which
lived between 40-50 and 100--120 fathoms depth and from which he
deduced the depth a t which the crustaceans lived. The specific
characters, as given by Sars (in Latin) are as follows :
Whitish, translucent, spotted above with red. Cephalothorax equalling a third
to three-eighths of the whole body in length; with the forehead very short and
truncated, not reaching the slender stalks of the very large eyes, with the
median anterior edge angular (rostrum rudimentary), with a sharp spine on both
sides of the triangle. Antennae as in T. inermis. Only seven pairs of gills, with
none on the first pair of feet, very large on the hindmost. The gills consist of
short double curved branches, with a single row of simple tufts in the six
anterior pairs, covered with secondary tufts of pinnate embellishments in the
last pair.
I n a subsequent paper, Sars (1864a) gave a fuller synopsis of the
species in which he included a description of the photophores or lightproducing organs that it, like other euphausiids, possesses. His
description, again in Latin, of these organs reads as follows :
There occur ventrally eight sensitive spherical organs (undoubtedly simple eyes),
with hemispherical transparent corneas, otherwise pigmented with a milky
purple, with separate small crystalline lenses within the cornea. These organs
are embedded in the first segment of the second and seventh pairs of thoracic
limbs and in the centre ventrally between the first four pairs of abdominal
limbs.
THE BIOLOGY O F EUPHAUSIIDS
species Thysanopoda krohnii and T . longipes were described by Brandt
(1851).
Another species of Thysanopoda was described by Bell, who in 1853
published his History of the British stalk-eyed Crustacea. He included
the genus Thysanopoda, with the characteristics given by MilneEdwards, in the family Mysidae. He added a note to the effect that the
eggs were contained in a pair of oval sacs dependant from within the
bases of the posterior feet and so differing from those of other mysids.
Bell’s species was Thysanopoda couchii (now Nyctiphanes couchii),
large numbers of which were taken from the stomach of a mackerel
caught in the English Channel.
At a meeting of Scandinavian biologists held in Christiania (now
Oslo) from 12-18 July, 1856 the great Norwegian zoologist Michael Sars
described three new crustaceans (Sars, 1857). One of these represented
a new mysid genus and was called Lophogaster typicus; the other two
were species of Thysanopoda, T . apiops and T . norvegica (now
Meganyctiphanes norvegica). Sars obtained four specimens of Thysanopoda norvegica from Floro and Sondfjord in Norwegian waters. They
were about 2.5-4.0 cm in length, of which the cephalothorax formed
about one-third. He also had a further nine specimens from the guts of
two Norway haddocks, Sebastes norvegicus (=S. marinus (L.)), which
lived between 40-50 and 100--120 fathoms depth and from which he
deduced the depth a t which the crustaceans lived. The specific
characters, as given by Sars (in Latin) are as follows :
Whitish, translucent, spotted above with red. Cephalothorax equalling a third
to three-eighths of the whole body in length; with the forehead very short and
truncated, not reaching the slender stalks of the very large eyes, with the
median anterior edge angular (rostrum rudimentary), with a sharp spine on both
sides of the triangle. Antennae as in T. inermis. Only seven pairs of gills, with
none on the first pair of feet, very large on the hindmost. The gills consist of
short double curved branches, with a single row of simple tufts in the six
anterior pairs, covered with secondary tufts of pinnate embellishments in the
last pair.
I n a subsequent paper, Sars (1864a) gave a fuller synopsis of the
species in which he included a description of the photophores or lightproducing organs that it, like other euphausiids, possesses. His
description, again in Latin, of these organs reads as follows :
There occur ventrally eight sensitive spherical organs (undoubtedly simple eyes),
with hemispherical transparent corneas, otherwise pigmented with a milky
purple, with separate small crystalline lenses within the cornea. These organs
are embedded in the first segment of the second and seventh pairs of thoracic
limbs and in the centre ventrally between the first four pairs of abdominal
limbs.