488 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Ptychodera has an outer circular musculature, Glandiceps and Schizo - 
cardium have internal circular muscles, while in the true Balanoglossua 
there are no circular muscles. 
Geographical Distribution of Marine Rotatoria.* — Dr. E. v. 
Daday gives a list of marine Rotatoria, and tabulates (i.) those (28) species 
that are exclusively marine, (ii.) those (32) that are marine and lacustrine, 
(iii.) those (6) that are marine and lacustrine aud also found in inland salt 
lakes. He further gives lists of the Rotifers found in the sea and inland 
salt lakes, in freshwater lakes and salt lakes, and in fresh and brackish 
water. 
From these lists it is very evident that marine Rotifers have not yet 
been properly sought for by naturalists, for Dr. Daday can only enumerate 
3 species from the North Sea, 2 from the Indian Ocean, and 1 [and that 
one wrongly] from the Pacific, and none at all from the Atlantic. We 
think Dr. Daday could have found a few more marine species by care- 
fully looking over the pages of Hudson and Gosse’s monograph ; 
Salpina marina , Diaschiza fretalis , Diglena suilla, Notholca scapha , 
Distemma platyceps , Furcularia sphserica , and some more are therein 
indicated as marine. 
The author, however, makes a mistake in including Trochosphsera 
sequatorialis among the marine forms ; this species was first found by 
Dr. Semper in freshwater pools of rice fields in the Philippine Islands, 
and recently by Surgeon Gunson Thorpe, R.N., in a pond in the 
Botanical Gardens of Brisbane, Australia ; there is no record of its 
having been found in the sea. 
We notice also that Dr. Daday uses many names which have been 
changed by the new classification of Hudson and Gosse. Their 
admirable monograph being the only book of reference extant for 
Rotifers, we cannot help thinking that all workers in this field will 
avoid much confusion by calling the Rotifers by the generic names 
therein given them. 
Studies on Rotifers.t — Dr. C. Zelinka, prompted by the desire to 
set at rest all doubts as to the relationships of Rotifers to the larvae of 
Annelids, has made a series of important anatomical and embryological 
studies. 
He begins with a detailed account of the structure of Callidina russeola 
with which other species are compared. He emphasizes the necessity 
of taking account, in all determinations of species, of the following 
characters — maximum length, relation of length and breadth in creeping 
and rotating, the form of the “ rotatory organ ” and upper lip, the colour 
of the gut and of the skin, the nature of the skin, whether spiny, warty, 
granular, or otherwise, the form and size of the jaws and their position 
in the body when extended, the number of teeth, the form of the foot, of 
the prongs, of the terminal joint, the form of the proboscis, the position 
of the gonads, and the number of ciliated lobes. 
Zelinka then discusses the symbiosis between Rotifers and liverworts . 
and three new symbiotic species are described. He devotes some care 
to answering Goebel’s criticism of his previous observations on this 
* Math. u. Naturw. Ber. aus Ungarn, ix. (1891) pp. 55-66. 
t Zeitschr. f. Wiss. Zool., liii. (1891) pp. 1-159 (6 figs, and 6 pis.). 
