614 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Nectonema agile.* — Mr. H. B. Ward gives a detailed account of 
this pelagic worm, the systematic position of which is a matter of some 
difficulty. He himself thinks that, though the points of difference 
between it and Gordius are more numerous than those of resemblance, 
the latter are more general and important. The characters which 
separate the Gordiidae from the rest of the Nematoda are possessed by 
Nectonema — the absence of lateral lines, the existence of one principal 
nerve-cord (ventral), the dorsal position and terminal openings of the 
genital organs. The points of difference are largely those which separate 
the various families of Nematodes from one another, such as the struc- 
ture of the muscles, and the characters of the ducts and external sexual 
organs. 
Mr. Ward thinks that the greater reduction of the alimentary canal 
and of the nervous system in Gordius is evidence of its being the more 
degenerate form. The possession by Nectonema of rows of bristles is 
certainly to be attributed to its free life and more active habits. Further 
and more definite decisions as to the position of Nectonema may be 
delayed till its life-history has been investigated. It is probable that 
till sexual maturity Nectonema is parasitic in some fish or crustacean, 
and the absence of eye-spots or sense-organs, the diminutive size of the 
alimentary tract as compared with that of the animal, and the absence of 
any functional anus are all characters that point to the parasitic nature 
of the worm. When free it appears to come to the surface at night 
only. 
Structure of Echinorhynchus.| — Dr. J. Kaiser continues his account 
of the minute structure of this type. He is first concerned with the 
musculature of the proboscis — its structure and development. He 
describes this not only for the musculature as a whole, but for each set 
of muscles. Passing to the nervous system he gives first the usual 
history of investigation, then his own observations. The central nervous 
system consists of a cephalic ganglion of considerable size, lying between 
the retractors of the proboscis at a variable distance from the posterior 
end of the proboscis sheath. In EchinorJiynchus gigas the ganglion gives 
origin to not less than eight nerve-strands, but in other species there are 
fewer. The minute structure of ganglion and nerves is analysed with 
great carefulness. Embryological investigations confirmed Herr Kaiser’s 
conviction that both ganglion and nerves had an ectodermic origin ; the 
same is true of the special genital ganglia. The present instalment of 
this monograph breaks off in the middle of the chapter on the male 
genital organs, 
Helminthological Notes.J — Prof. M. Stossich continues his descrip- 
tion of a collection of Venetian parasites made by Dr. A. Conte de 
Ninni. Among the forms noted are Gucullanus Dumerilii , Monostomum 
trigonocephalum , Distomum JRaynerianum, EchinorhyncJius Ninnii, Tsenia 
brachycepliala , Amphicotyle typica. 
* Bull. Mus. Comp. Zool., xxiii. (1892) pp. 135-89 (8 pis.). 
t Bibliotkeka Zool., Heft 7 (1892) pp. 113-36, and Heft 8, pp. 1-32 (1 pi.). 
X Boll. Soc. Adr. Sci. Nat. Trieste, xiii. (1891) pp. 109-16 (1 pi.). 
