620 NOTES ON PROSOBRANCHIATA. No. W.—LITTORINACEA. By H. Leighton Kesteven. (Plate XXX.) When studying the affinities of Fossarina (9), I found that Risella differed in anatomic characters from Littorina, the type genus of the family, to which, in the past, it has been assigned. I have since studied its anatomy from actual dissections and from sets of serial sections, kindly prepared for me by Messrs. J. P. Hill and R. Greig Smith. My thanks are also due to Mr. C. Hedley for many useful suggestions. I have also dissected Tectarius and Littorina. As a result of comparing the anatomy of these with other Tsenioglossa, I have found it advisable to reclassify the Littorine groups thereof. It will be as well to state my conclusions first and discuss them in detail afterwards. I have taken as my base Fischer's classification (4, pp. 707-711), and have altered it in the following manner : — Superfamily LITTORINACEA. Family LITTORINID^.* Containing those genera enumerated hereunder by Fischer, with the exception of Fossarina (which in my paper above referred to has been shown to be a Trochid), Risella and Echinella. * In defining Littorinidae thus I have had to take a good deal for granted, since there have been no dissections of several of the genera published; nor have I been able to study the soft parts of any but Australian members. I have been unable to obtain even the shells of some of the genera. It is probable that, as our knowledge of Prosobranchiate anatomy increases, several of them will have to be removed. I
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