318 SUMMARY OF QUERENT RESEARCHES RELATING TO 



turning the shell end for end and frequently throwing it some inches. 

 If the shell overbalances the foot, as more frequently happens, the foot 

 shoots anteriorly with the flaps spread, with a speed peculiar to this 

 movement. Starting with a direct push on the bottom (of the aquarium) 

 and followed by that upon the water, such a movement usually results in 

 a very considerable leap ; the shell being thrown posteriorly. These 

 leaps follow each other so rapidly that it frequently happens that the 

 shell hardly touches bottom before another leap is made. In this case 

 the protruded foot is bent dorsally and then makes an antero-ventral 

 sweep, the flaps being spread at the instant the sweep begins, and shut 

 together when the foot is at its greatest protrusion. The musculature 

 involved is then discussed. 



There is still another method of locomotion to be described, — that of 

 swimming. In Solenomya, the anterior end of the shell is pointed for- 

 ward, and the movement consists of a series of short darts that remind 

 one of the swimming of a squid. Each dart is accompanied by certain 

 movements of the foot that are very misleading when considered by 

 themselves. It does not burrow through the water, but moves by a some- 

 what complex process of expelling jets of water. Very possibly the jets 

 are of use in cleaning the mantle chamber and burrow, and the animal 

 has made use of them secondarily for locomotion. 



Chinese Mollusca.* — M. Bavay notes the discovery in South China 

 of Unio ajjinis Hende, a species which, like many of its allies from the 

 Yang-Tse-Kiang, shows a strong resemblance to the Unios of North 

 America. The suggestion of affinity between the Molluscan fauna of 

 the two countries is confirmed by two other facts of similar nature. In 

 the north of Tonkin there occurs a species of Anculotus Say, a member 

 of the family Strepomatidse, hitherto supposed to be confined to North 

 America. In the Yang-Tse-Kiang and its tributaries the same or a 

 closely allied species of Anculotus occurs, in company with what appears 

 to be a species of Pleurocera, another Strepomatid hitherto only known 

 from North America. 



Arthropoda. 



o. Insecta. 



Census of an Ant-hill.j — Prof. E. Yung has tried to take a census 

 of the ant-hills of Formica rufa. His method was to place a board 

 of wood on the hill, to brush off the ants which immediately cover it 

 into a vessel with spirits of wine, and to repeat the operation for an 

 hour or two, day after day, and even week after week, until the nest was 

 thoroughly depopulated. The results were : — 



* Bull. Soc. Zool. France, xxiv. (1899) pp. 212-3. 



t Arch. Zool. Expe'r., vii. (1899) Notes et Kevue, pp. xxxiii-v. 



