312 NATURAL SCIENCE. April, 1894. 



The temperature of the bottom mud seems to be somewhat 

 higher than that of the water in winter ; for instance, while the 

 water was about o'^C, the temperature 3-4 feet down in the mud was 

 + 7° C. This is doubtless the reason why many animals (Gobiidae 

 Cavcinns, Cerithium, etc.) bury themselves in winter. The influence of 

 the physical conditions on the distribution of various animals is then 

 discussed, and fourteen examples are given in some detail, special 

 reference being made to different species of the same genus which 

 appear to represent each other in different parts of the area under 

 consideration. The author claims to have shown " that each species 

 is distributed according to certain rules," it is seldom, however, "that 

 one single factor is decisive, but the distribution is the result of 

 groups of concurrent circumstances." One point of interest is brought 

 prominently forward — " no species of animal is found everywhere in 

 our seas." When an animal is once recognised as common it is 

 usual in faunistic works to describe it as found " in all our sounds and 

 fjords" as occurring "everywhere along the Danish shores," so that 

 frequently the more abundant a species the less information is available 

 as to its actual distribution. Dr. Petersen's careful maps 

 furnish a marked contrast to this mode of work. After a short 

 chapter on the distribution of certain animals outside the Danish 

 waters, we have some observations on distribution in the post- 

 Glacial period, from which it appears that the Baltic and Kattegat 

 may be compared to a Norwegian fjord in which the cold water forms 

 are not yet shut in, but in which they and the warm water forms 

 move in and out according to circumstances. As representatives of 

 the "cold fauna" we have Astavte borealis, Idotea entomon, Halicryptus 

 spinuloses, etc., of the " warm fauna" Ostrea edulis, Tapes pullasiva, 

 and Pectcn variiis. This concludes a most important and interesting 

 contribution to the natural history of the Kattegat — " the greatest 

 battlefield on the coast of Europe between the ocean water and the 

 fresh water." 



Wm. E. Hoyle. 



The British Oniscidse or " Woodlice" — a group of animals some- 

 what neglected by naturalists — are described by Dr. R. F. Scharff in 

 the Irish Natumlist for January and February, all our native species 

 being well figured on a single plate. Fourteen species are common 

 to Great Britain and Ireland, two occur in the large island which are 

 not found in the smaller, while three species have been found in 

 Ireland which have not yet been observed in England or Scotland. 

 There are not many groups in which Ireland can claim a richer fauna 

 than Great Britain. Foreign species receive attention at the hands of 

 M. Adrien Dollfus, who continues his researches^on the Isopoda and 

 their geographical distribution. Four of his papers have recently 

 come to hand, and furnish us with information on the woodlice of 

 Venezuela, ihe Pyrenees, and the Seychelles. 



The Termite Ants are so constantly being brought forward in discus- 

 sions on Natural Selection (see Mr. Piatt Ball's paper, Natural 

 Science, Feb., 1894, and Mr. Cunningham's in the present number), 

 that those interested in the problem will be glad to know of an 

 exhaustive paper on the constitution and development of the Termite 

 colony, with notes on their habits, which is now begun by Drs. 

 B. Grassi and A. Sandias in AHi della Accademia Gicenia in Catania (ser. 

 4, vol. vi.). 



