574 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
matous origin, and come from many scattered cells united secondarily. 
It follows that the sharp lines drawn by speculative morphologists as 
to enterocoels, schizocoels, and blastocoels are fading out as evidence 
comes in. “ Phylogenetic speculations of far-reaching and of supposed 
fundamental import, based on the origins of mesoderm in different 
groups, are losing their hold as facts accumulate.” 
With regard to the nerve-cord, Mr. Morgan believes that it is a great 
error to speak of the invaginated dorsal cord of Balanoglossus as equiva- 
lent to the whole of the dorsal cord of the higher Chordata, because this 
cord in Balanoglossus stretches through only a single metamere of the 
body, and does not give off and receive nerve-fibres along its length. It 
corresponds, therefore, to the anterior end only of the nerve-cord of 
Amphioxus , the homologue of the rest of which is to be looked for in the 
superficial dorsal nerve-tract which stretches through the gill-region to 
the end of the body. 
Pedalion.* — Herr K. M. Levander gives a full and detailed account 
of the structure of P. fennicum which he constantly compares with 
P. mirum. With regard to the wider question of the origin of the 
Eotatoria and their relations to the Crustacea, and to the Trochophore- 
larva he sides with Dr. Plate rather than with Prof. Lankester, 
recognizing that the appendages of this Rotifer are not confined to the 
ventral surface, and that they may be unpaired. He considers, indeed, 
that they are rather secondary structures, for in other points of the 
organization of Pedalion he finds nothing essentially different from the 
Rotatorian type. He dismisses with a word Daday’s attempt to 
homologize the digitate appendages of the hinder end of P. mirum with 
the furca of Nauplius. The development of arthropod-like extremities 
traversed by muscles must be looked upon as an example of the phe- 
nomena of convergence. 
Rotatoria of Michigan.f— Mr. H. S. Jennings has a report on the 
Rotifers of the Great Lakes and of some of the inland lakes of Michigan. 
In the enumeration of the 122 species Hudson and Gosse’s monograph 
has generally been followed ; of these species six are new ; they are 
Notops laurentinus , Notommata monopus , N. truncata , Mastigocerca lata , 
Battulus sulcatus, and Salpina macrocera. 
It is curious that the two common forms, Lacinularia socialis and 
Hydatina senta, which are reported from almost everywhere, were never 
found in the waters examined by the author. 
Echino derma. 
Hsemal and Water-vascular Systems of Asteroidea.if — Mr. H. C. 
Chadwick, at the suggestion of the late Prof. Milnes Marshall, undertook 
a re-examination of the vascular system of Starfishes, based on a study of 
Asterias, Cribrella , Astropecten, and Asterina. He states his results, and 
compares them with those of the numerous previous workers on the 
subject. 
* Acta Soc. Faun, et Flor. Fenn., xi. No. 1 (1894) 33 pp., 1 pi. 
f Bull. Michigan Fish Coram., No. 3 (1894) 34 pp., 1 [double] pi. 
X Trans. Liverpool Biol. Soc., vii. (1893) pp. 231-44 (4 pis.). 
