184 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
the muscle-plates are genetically connected with the ectoderm or with 
the endoderm. The blastopore has no relation whatever to the mouth 
or to the anus. 
At the anterior edge of the blastopore there is a very peculiar 
differentiation of some of the ectoderm cells ; seventeen or nineteen 
rapidly form a transverse curved band in front of the blastopore, and 
then give rise by budding to smaller cells. In this way there is formed 
an ectodermal germ-stripe, formed of seventeen or nineteen rows of cells. 
This band extends forwards as far as a line which unites the points of 
insertion of the right and left mandibles with one another. In front of 
this line there is a mosaic of polygonal ectodermal cells. The ventral 
ectoderm, it is of interest to observe, becomes differentiated into a 
naupliar and a “ metanaupliar ” rudiment ; the naupliar appendages grow 
out from the anterior cell-mosaic, while all the appendages behind the 
mandibles owe their origin to the germ-stripes derived from the primi- 
tive cells. Behind these last there is, at an early stage, an embryonic 
(provisional) forked tail-fin, which is very distinct in the nauplius-stage. 
The history of the ganglionic cells is not unlike that of Insects, as 
described by Wheeler, but in My sis, the neuroplasts are not overgrown 
by epidermis, but form always the most superficial cellular layer in 
their own region. There are in the history marked points both of 
agreement with and divergence from that of Gammarus. 
Structure of Cypridse.* — Prof. C. Claus gives a general account of 
the structure of Cypridae, describing the position of organs, the shell, 
the antennae, the upper lip, liypostome, and mouth-parts, the legs and 
furcal pieces. Some new facts are added, some old statements are cor- 
rected. Diagnoses and descriptions are given of some South American 
forms — the genus Acanthocypris Cls., the species A. bicuspis Cls., the 
genus Pachycypris Cls., and two new species P. Leucharti and P. incisa. 
The Genus Copilia (Sapphirinella).f — Dr. F. Dahl gives the specific 
diagnosis, synonymy, and distribution of Copilia mirabilis Dana, C. medi- 
terranea Claus, C. lata Giesbr., C. quadrata Dana, and C. vitrea Haeckel. 
He gives tables showing the occurrence and the characters of the males 
and females, for in this genus, as is well known, there is marked sexual 
dimorphism. The species occur only in the tropical and subtropical 
regions. In the Atlantic the region of currents is much richer than the 
Sargasso Sea and the region between Ascension and Brazil. Two 
species, C. lata and C. vitrea , occur almost uniformly distributed ; 
C. mediterranea is not found south of Cape Yerde ; C. mirabilis is absent 
from the Sargasso Sea and the north-east region ; C. quadrata was not 
found in the south-west, but was abundant between Cape Yerde and 
Ascension and in other parts. All are very rare, if not absent, at depths 
below 700 metres. 
Vermes. 
a. Annelida- 
Asymmetrical Growth in Polychseta.J — M. de Saint-Josephs has 
observed that, in many species of Sabellidae, the number of thoracic 
* Arbeit. Zool. Inst. Univ. Wien (Claus) x. (1892) pp. 147-216 (12 pis., 3 figs.). 
f Zool. Jahrb., vi. (1892) pp. 499-522 (1 pi.). 
X Comptes Rendus, cxv. (1892) pp. 887-90. 
