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SUMMARY OF CURRENT RESEARCHES RELATING TO 
which favour the development of the statoblasts, and describes the 
complex internal processes which then occur. The germinating stato- 
blast is equivalent to a single bud of the stock, or to a single cystid 
with its associated polypide. But in the stock the cystid developes from 
the polypoid bud, while the reverse is true of the statoblast, in which 
the cystid is primary and gives rise by folding and contraction to the 
polypide. The statoblast is like a bud, but with an inversion of the# 
germinal layers. The bud is an individual developing from the poly- 
pidal pole with a secondary formation of the cystid; the statoblast is an 
individual developing from the cystidal pole with a secondary formation 
of the polypide. Dr. Braem also describes the sexual reproduction, 
which in a general way may be thus contrasted with reproduction by 
statoblasts : — The statoblast is an individual formed by budding, retained 
within the maternal colony, destined after the death of the latter and a 
resting period to continue the old stem ; the fertilized ovum leaves the 
maternal colony while that still lives and is destined to begin a new 
stem. The embryonic cystid of the larva is a formation mi generis , and 
not comparable with the external part of the statoblast rudiment. This 
important memoir, the nature of which we have merely outlined, closes 
with a description of Paludicella Ehrenbergii . 
B. Bryozoa. 
Free Development in Ectoproctons Bryozoa.* — M. H. Prouho calls 
attention to three cases of free development in this group ; these are 
represented by Alcyonidium albidum, Membranijpora pilosa, and LLypo- 
pliorella expansa ; as these three forms differ not only in important mor- 
phological characters but in habitat and habjts we may conclude that 
the Cyphonautes form is the larva of all Bryozoa whose ova undergo 
free development. 
y. Brachiopoda. 
Anatomy of Lingula, j — Dr. P. Frangois found that Lingula anatina 
could be detected by a small cleft in the sand which closes suddenly. 
Having discovered this he was able to get, in less than an hour, thirty 
specimens, of all sizes, from *015 m. to *05 m. in length. This proves 
that the form lives for at least more than a year, and that it therein 
differs from its ally Glottidia, which, according to Morse, attains its full 
development in one year. Lingula lives upright in its burrow, the 
upper part of the shell being flush with the surface and projecting at those 
points which correspond to the three tufts of long setae on the upper 
edge of the mantle. The burrow in which it lives is not a tube in the 
sense of the “ tube” of Annelids, for the sand is merely pushed aside, 
while the interior is lined with mucus secreted by the Lingula. The 
peduncle is greatly elongated and its lower part is lodged in a true tube 
of sand agglomerated by mucus ; when the creature feels the approach 
of danger, the peduncle is suddenly contracted on itself, and the shell 
brought down to the mouth of the tube ; the downward movement is 
effected as rapidly as that of a Serpula, and it often results in the com- 
* Comptes Kendus, cxii. (1891) pp. 131G-8. 
t Arch. Zoo]. Exper. et Gen., ix. (1891) pp. 231-9. 
