76 SUMMARY OF CUERENT RESEARCHES RELATING TO 



several. From this ring filaments run to the hook musculature, while 

 from ganglionic swellings eight branches descend, four going to the 

 two principal lateral ganglia, and four prolonging their course even 

 within the proglottides. The ring ganglia in T. coenurus also give 

 origin to nerves going directly to the suckers. 



(h) The central ganglion. — In the middle of the " principal " com- 

 missure joining the two lateral ganglia, there is a large central 

 ganglion, from which a "transverse" commissure passes at right 

 angles to the " principal." 



(c) Polygonal commissures. — In the plane of these two chief com- 

 missures there lie nerves, which unite the two lateral ganglia with the 

 branches descending from the nerve-ring and with the " transverse 

 commissure," thus forming a polygonal figure, parallel to which, a 

 little below, there lies an "inferior polygonal commissure" of the 

 same nature. Where the diflferent branches join, " secondary ganglia " 

 are situated, and from these, as well as from the principal lateral 

 ganglia, the suckers are supplied with nerves, four to each. 



(d) The "spongy cords." — Nitzsche had previously observed ten 

 " spongy cords," which Niemiec now enables us definitely to localize. 

 Six of them, three on each side, start from the principal lateral 

 ganglia ; the remaining four have been already noted as descending 

 from the nerve-ring and passing through the " secondary ganglia." 



Dr. Niemiec indicates the interest of his research as a contribution 

 towards the solution of the problem of the phylogeny of the Cestodes. 

 (1) He enumerates the resemblances between the nervous system of 

 Tsenise and that of TetrarhyncM, recently elucidated by Lang. (2) 

 While acknowledging the difficulties of the comparison he regards 

 the nerve-ring of Tsenise — not the commissure — as homologous with 

 the oesophageal ring of Annelids, from which it differs only in its less 

 pronounced development or reversion to a more rudimentary form. 

 (3) Eeferring to the recent researches of Lang and Gaffron on Tre- 

 matodes, he indicates how they lessen the difference between the 

 Cestode and Trematode nervous systems, which his own discoveries 

 seem to increase. 



Natural History of Rotifers.* — In the first portion of his essay 

 Dr. L. Plate gives a full account of the fresh-water Eotifers examined 

 by him ; they are thus arranged : — 



Pam. Tubicolarina : Lacinularia socialis, Conochilus volvox. 

 „ Philodinaa : there are here some general notes. 

 „ Polyarthraa : Polyarthra platyptera, Triarthra longiseta, T. 



terminalis n. sp., and T. cornuta. 

 „ Hydatinaa : Notommata aurita, N. vermicularis, N. lacinulata, 



N. tripus, N. hyptopus, Lindia torulosa, Hertwigia volvocicola 



n. sp., Eosphora elongata, Hydatina senta, Synchseta pectinata, 



S. tremula, and Bhinops vitrea. 

 „ Macrodactylea : Scaridium longicaudatum, Monocerca rattus, and 



Diurella tigris. 



* Jenaisch. Zeitschr. f. Naturwiss., xix. (1885) pp. 1-120 (3 pis.). 



