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f u r c a 1 lamella has seven claws, which decrease fairly uniformly in length and strength
the more proximally they are situated.
Stage IV: — Shell: Average length, 1,2mm. In the third larval stage the bristles on
the surface of the shell are somewhat fe wer than in the first and second stages; this decrease is still
more striking in this stage, the surface of the shell being almost smooth. The s i x t h 1 i m b is
represented by a rounded, unjointed or almost unjointed, two-lobedplate; cf. fig. 20 of this species
in the special part of this work; the proximal lobe is only furnished with one bristle, the distal one
has no bristles, armed only with long, stifï hairs. The s e v e n t h limb is also found; it is
repre-sented, however, only by a small, undifïerentiated process pointingupwards. Each f u r c a 1 lamell a
has six claws, which decrease fairly uniformly in length the more proximally they are situated.
Stage V: — Shell: Average length, 1 mm. Even in this stage the shell has about the
same shape as that of the mature female. The dorsal margin is, however, somewhat more uniformly
rounded. The s i x t h 1 i m b is less fiattened and is simple, peg-like, without bristles, furnished
only with stifï hairs. The cleaning limb is quite absent. The anterior limbs are
also of a decidedly larval type, with a very much reduced number of bristles, but yet of about the
definitive type. Each furcal lamella is armed with from three to five claws, of which
the two distal ones dominate very decidedly over the others in size and strength; the proximal
ones are very weak, spine-like; cf. fig. 21 of this species in the special part. The
rod-shaped organ and median eye are well developed as in the preceding stages, but
have a very pronounced embryonal character.
This was the youngest freely living stage I found.
Stage VI: — This is hypothetical, as no specimens have been found so far.
The average length of the shell, as calculated theoretically, = 0,83 mm.
Stage VII: — This is still in the brood chamber of the mother. Shell: Average
length, 0,7 mm. It is oval; the rostral incisur is broad and rather shallow. The sixth
and seventh limbs are absent. The other limbs are developed with about the
definitive type; the posterior ones have, however, rather few bristles.
Meas urement s: -
142 specimens of this species from the abo ve-mentioned station were measured. The
measure-ments of the lengths of the shells gave the following result as shown graphically, fig. XXI.
It follows from this figure that the specimens investigated could be divided into six
distinct classes of length. In each dass the length differs by about three divisions. The
dass 80—82 consista of mature females (there were no mature males in this sample), the others
consisted of larvae. I succeeded in distinguishing males and females only in the two oldest
larval stages, as is shown above; both sexes appeared to have the same length of shell. Thus
classes 54—56 and 68—70 include both males and females.
The gro wth-f actor as determined empirically was 1,23,
With tliis growth-faetor the following average lengths are to be expected theoretically:
Stage V Stage IV Stage III Stage II Stage I Mature individuals.
29 d 36 d 44 d 54 d 66 d 81 d
28—30 d 34—36 d 43—45 d 54 56 d 68—70 d 80—82 d. Actual lengths.
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