344 SUMMARY OF CURRENT RESEARCHES RELATING TO 



of the latter, at first oblique, become straight as they approach the 

 middle line, and resemble a rectus. 



Small cylindrical longitudinal muscles are frequently cut off from the 

 mesio-dorsal portion, along the mid-dorsal line in the interspaces of the 

 dorsal fins. These are the supracarinales of Owen. Similar muscles are 

 frequently cut off from the mesio- ventral portion along the mid-ventral 

 line. These are the infracarinales of Owen. A small muscle, whose fibres 

 are usually distinguished by their red colour, is cut off from the latero- 

 dorsal portion and occupies the slope of the furrow in which the lateral 

 nerve is situated. A corresponding muscle is cut off from the latero- 

 ventral portion immediately below the lateral line. 



Relict Fauna. — Esben Petersen* discusses the Trichoptera, Ephe- 

 merida, and Plecoptera of the cold streams and wells of Jutland, and 

 calls attention to those forms which become sexually mature at a low 

 temperature, and are relics of colder ages. 



Sig Thorf deals with probable remains of a glacial Hydracarine fauna 

 persisting in Danish streams, viz. Spterchon (Hiqndosperchon) elegans 

 Sig Thor, Megapus nodipalpis Sig Thor, Hygrobates na'icus (Johnston), 

 Lebertia (Pilolebertia) insequalis (Koch), and Aturus scaber Kramer. 



0. Pesta| protests against regarding Nephrops norvegicus in the 

 Adriatic as a " glacial relict." Its distribution is probably determined 

 by the occurrence of a sandy and muddy bottom as much as by temper- 

 ature and depth. It occurs in the Bay of Biscay, on the coasts of 

 Morocco and Algiers, at Genoa and Naples. 



Plankton of Southern Alpine Lakes. § — G. Burckhardt has made 

 a systematic comparison of the plankton from Lakes Lugano, Como, and 

 Maggiore and that of Northern Alpine lakes. The general result is to 

 show a very striking resemblance both in composition and in distribu- 

 tion. 



Toothlessness of Myrmecophagidse.H — P. Adloff has cut sections of 

 two embryos of Cyclothurus didactylus, 6 cm. and 12 cm. in length, 

 and has found no trace of tooth-primordia or of a dental ridge. Thus 

 the investigations of Rose and Leche are confirmed — there is no evidence 

 that the Myrmecophagidas are other than quite edentulous. It is 

 possible, however, that younger embryos may show traces of teeth. 



Ciliary Mechanisms in Various Types. f — J. H. Orton describes the 

 ciliary mechanisms in Brachiopods and some Polychastes, and gives a 

 comparative account of the ciliary mechanisms on the gills of Molluscs, 

 Protochordata, Brachiopods, and cryptocephalous Polychretes, and of the 

 endostyle of Crepidula and its allies. Brachiopods feed in the same way 

 as some Gastropods, most Lamellibranchs, Amphioxus, and Ascidians, 



* Internat. Rev. Hydrobiol., vi. (1914) Biolog. Suppl. No. 3, pp. 1-9. 



t Internat. Rev. Hydrobiol., vi. (1911) Biolog. Suppl. No. 3, pp. 1-14 (10 figs.). 



X Internat. Rev. Hvdrobiol., vi. (1914) Biolog. Suppl. No. 3, pp. 1-6 (1 map). 



§ Internat. Rev. Hydrobiol., vi. (1914) Biolog. Suppl. No. 3, pp. 1-30 (14 figs.). 



|| Anat. Anzeig., xlvi. (1914) pp. 309-10. 



^ Journ. Marine Biol. Assoc, x. (1914) pp. 283-311 (12 figs.). 



