The spawn
is consequently exceedingly difficult to procure, and unfortunately it
becomes spoilt in a day when it is removed from its natural hatching
place, whilst on the contrary the progress of development may be
followed for weeks together in the eggs of a single Crab kept in
confinement. The eggs of Squilla, like those removed from the body of
the Crab, die because they are deprived of the rapid stream of fresh
water which the mother drives through her hole for the purpose of her
own respiration.
The accompanying representation of the embryo of Squilla shows that it
possesses a long, segmented abdomen without appendages, a bilobate tail,
six pairs of limbs, and a short heart; the latter only pulsates weakly
and slowly. If it acquires more limbs before exclusion, the youngest
larva must stand on the same level as the youngest larva of Euphausia
observed by Claus.
(FIGURE 34. Embryo of a Squilla, magnified 45 diam. a. heart.
FIGURE 35. Older larva (Zoea) of a Stomapod, magnified 15 diam.)
Of the two larval forms at present known which are with certainty to be
ascribed, if not to Squilla, at least to a Stomapod, I pass over the
younger one* (* 'Archiv fur Naturgeschichte' 1863 Taf 1.) as its limbs
cannot be positively interpreted, and will only mention that in it the
last three abdominal segments are still destitute of appendages.
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