70 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Ptychodera , and he proposes for it the specific name of australiensis It 
lias been found at such widely distant points that it may be looked for 
along the whole coast line of New South Wales. Specimens were found 
in abundance in a rocky corner of the ocean beach. Like the other 
species of the genus it is littoral and confined to very shallow water. 
The largest specimen found was a sexually mature male, which measured 
in the living condition, and when only very moderately extended, about 
12 <m in length. A still larger specimen measures as much as 18 crn., 
and this when fully extended reached a length of over 25 cm. All 
appear to be capable of very considerable extension. Sexually mature 
males and females can very easily be distinguished from one another by 
their different coloration. In the male the testes are of very deep 
yellow colour, while the ovaries are very light yellow or almost white. 
The present species is destitute of any odour. A large proportion of 
the individuals are infested by a parasitic Copepod of the genus Ives , 
but the author is not certain whether or no it is identical with the single 
member of the genus hitherto described as I. balanoglossi. A detailed 
account is given of the anatomy of this new species. The notochord 
is very like in shape to that of P. minuta. With regard to the 
histology of the cellular part of the chord, the author has never been 
able to observe in any of his preparations the giant ganglion cells 
described and figured by Spengel. In the structure of the gonads also 
this species does not seem to accord very well with the description given 
by the just-named anatomist. On the other hand, the author’s observa- 
tions on the gill- vessels confirm, so far as they go, the observations of 
Spengel. 
Reproduction of My'TQstomata.* — M. H. Prouho reminds zoologists 
that he wrote a prelimin iry note on the sexual characters of Myzostomes 
three years ago, since which time Mr. Wheeler has announced his dis- 
covery of the special conditions of hermaphroditism in this parasite. 
M. Prouho appears to claim a priority over Mr. Wheeler, although 
remarking that the American author has made some interesting observa- 
tions on the development of the ova. 
Echinoderma. 
Fertilisation and Cleavage of Echinoid Ova.f — Herr F. Reink e 
has, l'ko many others, turned his attention to the phenomena of fertilisa- 
tion and cleavage in the ova of Echinus microtuberculatus , Sphserrchinus 
granularis, and Strongylocentrotus lividus. He first studied the living 
ova, and got some interesting results by using Ziegler’s compressorium 
and artificially concentrated sea-water. Thus, he observed the marked 
amoeboid movements of the ovum-nucleus on the approach of the sperm- 
nucleus, and the impulsive movements of the segmentation-nucleus. 
Pressure dexterously applied greatly increases the rapidity of mitosis. 
In compressed ova, nuclear division often occurs without cell-division, 
mieromeres and macromeres are usually differentiated, the spindles are 
always at right angles to the direction of pressure, and generally, as 
Hcrtwig has shown, in the line of the largest plasma-masses. 
* Zool. Anzeig., xviii. (1895) pp. 392-5. 
t SB. K. Preuss. Akad. Wiss., 1895, pp. 625-37. 
