ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 289 



Brain of Isistius brasiliensis.* — R. Burkhardt has a note on the 

 brain of this rare abyssal Selachian, remarkable in having its olfactory 

 bnlbs without peduncles, and situated at a great distance from the 

 olfactory mucous membrane. In its general form the brain recalls that 

 of Teleosts. The peculiarity is associated with the size and position 

 of the eyes. In Teleosts likewise, the size and position of the eyes 

 of the embryo are important in determining the configuration of the 

 brain. 



Fresh-water Fishes of Borneo. f — L. Vaillant makes a preliminary 

 note on a rich collection acquired by the museum at Leyden. It in- 

 cludes 21 new species, including four new genera : — Pseudolais tetra- 

 nema and Sosia chamceleou belonging to the Siluridae, and Gyrinocheilm 

 pustidosus and ParhomalopUra obscura, belonging to the Cyprinidse. 

 Another noteworthy form is a new species of the little known genus 

 Aperioptus. 



The fresh-water fauna of Borneo, as regards fishes, is very homo- 

 geneous, and it presents close resemblances to the Indo-Chinese fauna. 



INVERTEBRATA. 



Relict Fauna of Lake Fureso.J — C. Wesenberg-Lund discusses the 

 animal population of this lake in Zeeland, which is very interesting in 

 connection with the question of relict faunas. Fureso includes some 

 remains of a marine fauna, the most ancient representatives of which 

 {Valvata, Bithynia, &c.) belong to a very old-established and almost 

 cosmopolitan fresh-water fauna adapted to lacustrine life at a period much 

 anterior to the Ice age, and of quite unknown origin. 



During the post-glacial epoch, which probably coincides with the 

 submersion of the isthmus which united Scania with the Danish islands, 

 towards the end of the period of Ancylus, there was a fresh immigration 

 enriching the Fureso fauna by two new forms at least, viz. My sis oculata 

 var. relicta, and Pontoporeia affinis. These two Crustaceans, which still 

 persist, are representatives of arctic forms whose immigration into the 

 inner Baltic must have occurred while that was in communication with 

 the Boreal sea. Their adaptation to fresh water must be referred to the 

 time when the inner Baltic became " le lac a Ancylus,' 1 '' and it occurred 

 in that lake. The other marine forms in Fureso probably immigrated 

 in much more recent times. Such geological knowledge as is available 

 forbids the idea that Fureso was an arm of the sea transformed into a 

 lake by an elevation of land or otherwise. Except Galigus lacustris 

 (brought by fishes ?), and perhaps Neritina Jiuviatilis (brought by birds, 

 &c. ?), the marine forms now actually isolated in Fureso have probably 

 arrived there in course of their own migrations. The presence in a 

 lake of a marine fauna is no proof that the lake was once an arm of 

 the sea. 



* Arch. Sci. Phys. Nat., xiv. (1902) pp. 534-5. 

 + Comptes Rendus, cxxxv. (1902) pp. 977-80. 



X Overset K. Datwke Vidensk. Selskab. Forhandl., 1902, No. 6 (published 1903) 

 pp. 257-303 (1 map). 



